I just spent eight days in Shanghai, and ate at a number of places based on recs I found here, as well as those from Chinese language sources (dianping and one Shanghai food guidebook). Here are some of my experiences.
Jia Jia Tang Bao: As widely reported here, JJTB is terrific. I went twice, and altogether tried the crab and pork (twice), pork and shrimp, and pork and egg yolk dumplings. I thought the crab/pork combo (19.5 RMB on the menu) was delicious, with the crab roe lending a beautiful richness. The pork/shrimp didn't seem all that special, while the pork/egg yolk combo was very tasty. There isn't much else on the menu (chicken and pork xlb, I think). A small saucer of ginger and vinegar is available for 1 RMB (vinegar is also free at your table), and there are a couple of soups (simple, clear broths mainly, with some things floating about) for 2 RMB - one has duck blood in it, so if you're squeamish don't choose one at random; the other (IIRC) had egg (?memory has lapsed a bit?). 90 Huanghe Lu near People's Square.
Shanghai Uncle: Had the 8 treasure duck (ba bao ya) as recommended here, which was good albeit pretty rich. The fat under the skin wasn't rendered as well as it should be, so the skin wasn't as crisp, either. This might bother some people quite a bit - I rolled with it. We also had the sword beans with minced pork, which was delicious. Would go back, maybe with a larger group of people, to try a bunch more of their dishes.
Merry Lin: Across the street from the Regent Hotel, it's a fairly well thought of Shanghainese restaurant. I think there's a cafe and a restaurant; we ate at the latter. We ordered red cooked lion's heads (hong shao se tze tou), the tofu with crab, and stir-fried grass-head (tsao tou). The se tze tou themselves were good, but I found the hong shao too sweet for my taste - but perhaps the Shanghainese like it this way. Tofu with crab was reasonably well executed and tasty, and the veg was very nice. I encountered a number of leafy green vegetables that I had never seen before (such as the tsao tou) and was told they are local Shanghai veggies. It was fun to try them, and it seems like 'hounds should try to expand beyond the normal veggies if they have the chance. Worth having a meal here if you're in the area.
Yang's Fry Dumplings: I tried a few sheng jian bao, and I just didn't find them all that inspiring. Yang's was the best of the bunch, but for whatever reason they just didn't do it for me. I'm accustomed to the more Taiwanese take on these, which I strongly prefer. Yang's did have a nice squirt of broth inside, so if you're into sjb, these are worth seeking out.
Nan Ling: A Yangzhou style (I think) restaurant that we were tipped off by an expat who had previously spent 8 years in Beijing as serving the best roast duck in Shanghai, though it isn't Beijing style. We ordered a half-duck (comes with extremely generous portion of pancakes, sliced scallions and cucumber, and hoisin sauce). The pancakes were the thin crepe style type, which I prefer to the thicker mantou kind. The duck skin was nicely crisp and flavorful. Also came with some duck meat which we very tasty, and here the fat had all been rendered off nicely. For 10 RMB we added a second duck dish, which turned out to be a small amount of duck stir-fried with yellow chives, which was absolutely terrific. Didn't get to try too many other dishes, but it seems worth exploring the menu more. On top of everything, the prices (can't remember exactly) were very reasonable. 168 Yueyang Lu
Shen Yue Xuan: I went (twice) to Shen Yue Xuan, a well-regarded dim sum house. The first time, we went to the Huaihai Road (near Huangpi Road) branch, the second time to the one on Huashan Lu (in the villa of a former Qing dynasty viceroy). The second is a great location, overlooking a park (which is strictly guarded with mean-sounding signs so you can't wander around), and I would definitely recommend it. Don't think there was much difference in price. Almost everything was very good to excellent. The dumplings were uniformly terrific. Skins were thin but held together nicely. The deep-fried dishes were also outstanding. Whoever's back there really knows how to fry. Everything came out hot and shatteringly-crisp. Congee was good as well, but not necessarily worth the lost real estate. Highlights: har gao was delicious, maybe the best I've had. There's a chive dumpling that is incredible - the filling is almost all chives, with a few bits of other stuff (should have dissected more carefully, but I was too busy enjoying it). Wow. 849 Huashan Lu (near Wukang Lu).
Ding Tai Feng: I've been to branches in Taipei and LA, and the Shanghai branch in Xintiandi seemed to have a slightly different menu from either of these other ones. I know others think it's overpriced, and in some ways it is, but if you don't live near one, I think it's well worth a visit. The highest praise I can give it is that almost all their dishes come out exactly as you want them to, both visually and taste-wise. I find the kitchen's consistency and the balance in the dishes very remarkable. The noodles at this branch were terrific, as were the desserts (sesame bun and almond pudding). We only had one order of the small Shanghai dumplings, which are smaller than normal XLB but very tasty. I don't think there's a bad meal to be had here, and wish I could eat my way through the entire menu. I also had a terrific Konig pilsener here - it seems that some of the nicer places have at least one interesting European beer on offer (though for many it's Bud, Heineken and Tsingtao).
Chuan Yu: A Sichuan restaurant in the mall above the Zhongshan subway station. Tried the la zi chicken, which was more ma than la, which I liked; the dofu hua with lots of spicy and salty additions was solid, though not particularly memorable; the spare ribs wrapped in sticky rice were very tasty; and the braised Chinese cabbage were pretty standard. I would go back to try other dishes on the menu.
South Beauty: I'd had a nice meal at one of the Beijing branches a few years ago, and this time checked out the incredibly beautiful location at 881 Yan An Zhong Lu (near Shanxi Lu). As a previous poster described, South Beauty seems like it shouldn't be great because it has a huge menu and is expanding like crazy, but somehow the standards are maintained at a high level. We tried the lan-style pork spareribs, which came as a one large rack, which they then carve for you on the spot. It came with a cumin-based rub and a topping of stir-fried chili peppers, green peppers, onions and a few other things. Spareribs were nicely cooked, with mostly moist succulent parts, a few nicely charred bits, and only a few dry spots. Expensive, though (~130 RMB IIRC), but a huge dish that can easily feed four, to six depending on how much each person wants. Also had a spicy braised eggplant which was came as long julienned strips and was absolutely terrific, although the portion was modest. The last dish we ordered were scallops wrapped in spinach and coated in almonds. Interesting, but it seemed to lack a dimension, like a sauce. Dipping it into the remaining spicy eggplant sauce improved things, but I wouldn't choose to order this one again. Overall, with the amazing setting and mostly terrific food, a place I look forward to re-visiting in the future.
Shanghai Lao Zhan (in English the Ye Olde Station Restaurant): A Shanghainese restaurant in the heart of Xujiahui, located in beautiful building that seems to be taken right out of the roaring 20's Shanghai, although the train in the middle courtyard is a bit much to say the least. Prices were surprisingly decent for a lot of dishes (but not, as usual, for the Shanghainese delicacies, e.g. hairy crab). We tried the famous crystal shrimp, which were stir-fried river shrimp, one of the local specialties. These shrimp are smaller than usual (maybe one-third to half the mass of your typical 16 to 20 count shrimp), with a very delicate flavor. Based on this single experience, I would venture to say that it is an exceptionally subtle dish and it was pulled off nicely here. I'm very glad I tried it, but if I lived in the area, I'd probably stick to other shrimp dishes for more everyday consumption. The yellow croaker in white wine sauce was outstanding, with a very nice balance of the wine and sugar, each complementing the other perfectly. Beautifully cooked fish as well. A real winner. Lastly tried the mushrooms with asparagus, which was also very good. I would definitely recommend this to visitors, given both the very cool setting and the excellent food, with surprisingly modest prices.
Jade Garden: There are a number of branches of this popular Shanghai and Cantonese style restaurant. We had the tea-smoked duck, which was very good - the meat was beautifully smoked and still a rather pronounced red color, which (as I've learned from the universally-loved Harold McGee) means that it was cooked at very low temperature. Also had the youbao river shrimp, i.e. fried whole in the shell with a sweet soy sauce-based sauce, another Shanghai specialty. I quite enjoyed trying it, but the sweetness was maybe a bit overdone (a problem that I find with a lot of Shanghainese food). I'd go back, but maybe not as frequently as some other places on this list.
Brothers Jiang: A chain of restaurants specializing in guo qiao noodles (literally "over bridge" noodles), I went to the one on (gasp) Nanjing Dong Lu. If you've never tried this Yunnan specialty, I'd recommend it if you like noodle soup. The strength of this dish was the broth, which had a very clean but nicely meaty-rich taste. With a huge number of great things to add (sliced meat, vegetables, mushrooms, etc etc) each bite was different. The red chili peppers pack a pretty big punch. My friend said that this branch tasted exactly the same as the one in Yunnan, so at least they're consistent. I'd definitely go back, and recommend it to visitors who haven't ever had this dish. Bonus is that it's very convenient from the hotels in the area.
Mister Donut: While I can see why people would like these donuts, I found them very average. It seems like the attraction would be that they're relatively low on the grease factor, as the fried-ness seems not to penetrate very deeply into the dough. To me, they can't hold a candle to hot-off-the-press Krispy Kreme, which is clearly an over the top grease and sugar experience, but it is a donut after all.
Tea Houses: There seem to be a bunch of tea houses throughout the city. I visited one, and it had a beautiful setting, and served mostly set-meal type food, where you choose a main dish and it came with a bunch of others. I thought the food was excellent and extraordinary value (25 RMB).
Bars: The bar at the Sofitel on Nanjing Dong Lu is a nice place to hang out. They make their own beer, which was OK but at least different from the usual. Great sofas to just sit/chat/relax. The bar at the top of the Hyatt in Pudong is pretty cool, albeit way pricey. One drink at those prices were enough for me. But it was fun to look down on the Pearl Tower after the lights went on (6:30 pm in mid-November). Note that this bar didn't open until 5 pm. Bar Rouge on the Bund was rather uninviting for their militant seating policies (minimum of 1000 RMB? to get a decent seat anywhere but right near the bar), both inside and out. But the view across to the Pudong side is pretty neat, as evidenced by all the tourists braving the cold to take photos while having a drink outside. I'd go once for one drink.
Lastly, there are lots of local places serving terrific street food. I definitely recommend poking around and trying different things. Maybe see where the locals go. Tthe XLB place just down the street served eight for 4 RMB, and they were really good. The dough was maybe a bit thicker than desired, but the filling every bit the equal of JJTB, although maybe a bit more rustic. Given the difference in convenience and price, I'd probably eat those 20 times for every special trip to JJTB.
Almost 2200 words! Wasn't there a time in the distant past i.e. high school, when 1500 words seemed like a long essay? Whew. I need a beer.