Second everything Steve noted, especially the lamb tagine. I had the savory version, from what I recall. The b'stila one of my dining companions had wasn't the seafood kind but was amazing regardless. The carrot salad was terrific; fortunately they were making it that day.
Also, the Turkish coffee is nice and strong and sweetened. I didn't think too much of their baklava (sp?).
I recommend over-ordering. Specifically ask if they have the seafood b'stilla. Many of their dishes will come with a house salad (simple but very tasty). Ask instead or in addition for a carrot salad. also make sure you get sides of both spinach and eggplant.
Lamb tagine is a must, plus they also make a very good chicken couscous. Baba ganoush is good as well.
Basically, you can't go wrong. The proprietress is from Morocco and her husband, who shares cooking duty, is from Egypt. So depending on who is doing the cooking they can prepare two very different tagines, one sweet with prunes, the other salty with olives.
Don't worry about the menu so much, as they sometimes prepare things whch are not on it. If you want something specific, I suggest calling them at (202) 232-6776 and request tfaya in advance. They told me they could even prepare an entirely Egyptian meal with a little advance notice.