Just got back from a trip to San Juan. We were not nearly as adventerous as we might have been food-wise, but did manage to get to a couple local places. For better or worse, here's the summary.
ON CALLE FORTALEZA ...
There's a block of restaurants near the taxi stand on Calle Fortaleza that cater primarily to yuppie tourists. Dragonfly is probably the best, based on the comments here and the line out the door every night. Unfortunately, we never did manage to eat here. Once the wait was looking to be well over an hour, another time they had stopped even adding names to the waitlist. The two places we did try were Parrot Club and Marmalade.
Parrot Club: Very crowded and very popular with tourists, but food just wasn't anything special. Not bad, but kind of bland. Service seemed to be spotty; while we got lucky and had no major problems, the table next to us had to wait over an hour between finishing appetizers and getting their entree.
Marmalade: Just as touristy as Parrot Club, and a little more pricey, but the difference is that the food was really enjoyable here. Great mixed drinks too. It's not local cuisine by any stretch of the imagination, but it's certainly a fun place with great food.
PUERTO RICAN PLACES ...
Casa Dante (39 Isla Verde Ave, about a mile or so west of the Isla Verde resorts): Probably the best food we had on the trip. The Mofongo, which is mashed plaintain with garlic and a little bit of pork, is absolutely outstanding. Basically, you get that with your choice of meat or fish; the entrees we tried were great as well. (You can substitute other sides, but Mofongo is their speciailty, so why bother?) Everything -- the Mofongo, the entrees, even the bread they bring out as a starter, is extremely garlicy, just so you know what you're signing up for. Only locals were there when we went, but we found the place in a guidebook and they have a review written in English on the wall, so I think they see plenty of tourists as well.
La Fonda El Jibarito (280 Calle Sol, in Old San Juan): Decent food here, not as good as Casa Dante, but the pork in plaintain sauce with a side of beans and rice still makes for a great hearty meal. Awful (slow, uninterested) service.
Ristorante El Popular (near Santurce marketplace): Saw a lot of locals here, and figured we ought to try it, but this was a miscalculation ... it was just mediocre bar food.
ISLA VERDE RESORTS ...
The Palm (El San Juan): Very good meal here. The steak may have been a little below average compared to the steaks I've had at other locations of this chain, but was still excellent. Lobster, salad, appetizers all outstanding.
BLT Steak (Ritz): Steak might have actually been a little better than the one at The Palm, but pretty much everything else was inferior, lobster over-cooked, salad no good, etc.
La Piccola Fontana (El San Juan): A pretty good Italian restaurant dressed up as if it were a great one ... and priced like it were a great one.
Mares (Ritz): The casual place at the Ritz. Uninteresting, but quality wasn't bad.