We are just finishing up 5 days in Mexico City DF - our previous stays were short ones on way elsewhere in the country. So, really, the first time we tried to experience the restaurant scene.
Varied experiences - have posted some thoughts on other threads, combining here with references for convenience.
Best experiences - El Cardenal for breakfast (reasonably priced, good local food experience, we didn't try dinner here), Dulce Patria for dinner (high end, pricey).
Izote - Have posted thoughts on the Izote thread with responses from others. Will only quickly summarize here - thought wasn't that great value overall (a bit on the pricey side), but, on the other hand, thought the fish we had was one of the best of the restaurants we visited in DF, and the desserts were memorable.
El Cardenal - We went twice to the one in Hilton (concierge at our hotel made table reservations and we didn't have to wait), and once to the one near Zocala (30 min wait for a table). We loved the atmosphere (lively, informal, friendly laid back yet attentive service), the bread (try the Concha with Nata - cream - delicious) which was always warm (unlike most other restaurants we visited), and thought prices were good value. For four of us, the costs for our breakfast were around $700 ... quite reasonable we thought.
Restaurant on top of Arte Mexicana para Mundo, on the south side of the Zocalo - worth a mention not for the food (though the coffee + sides we had were good), but for the great view of the Zocalo from the sixth floor.
Dulce Patria - Our best "high end" (as opposed to colorful local of El Cardenal) experience. We went back there a second time. Great food, atmosphere and service - our costs were $2600 and $2100 the two nights we went respectively (ex tip, ex alcohol, no dessert - didn't have space).
El Pendulo - Pros: free internet, nice relaxing atmosphere in a bookshop, outside/inside seating, fresh fruit juices in extra large cups, good guava jam. Cons - the bread was cold and dry, the price for breakfast for four at $750 was comparable to El Cardenal and we preferred the Cardenal experience.
Fonda El Refugio - A bit disappointed given the high recommendations.
Two of us ordered Red Snapper pan fried w/ garlic which was quite delicious. One ordered grilled red snapper which was dry and overdone. One ordered the Barbacoa (lamb) which was dry, stringy, and with little flavor. Sent it back and ordered the red snapper (pan fried) instead. The atmosphere felt a bit touristy - this place has been well discovered by now. Didn't appreciate the mandatory 15% gratuity
added on to our bill. The service was standard. Total ex tip came to $1300 - reasonable, but then again, it included the lamb that we sent back and the tip was about $200 on top.
Bondy - 38 Galileo, corner of Newton, Polanco; breakfast
Very nice experience - good bread, comparable to the best we had at other places (though they didn't have the nata we liked at Cardenal), fruit plate, four omelettes, juices, coffee total came to $600 (ex tip).
Azul Condesa - Overall good experience - please see the Izote thread for more.
We didn't get to try a number of other restaurants that are highly recommended: Cafe Tacuba, Pujol, Biko, Hacienda de Morales (sp?), etc. Plus, got very little exposure to street stalls on this trip.