he most important thing to note about Las Placitas is that they make moderately strong margaritas. If you have ever lived in Texas, you will probably complain about their overall taste, but you should go ahead and give them a shot.
The Tacos al Carbon I sampled were on par with the Texas taco chain Taco Cabana. Since I can get the same meal for about $10 less in Texas, it is hard for me to justify this particular order. Yet, this is DC. The only place I have visited with significantly better Tacos al Carbon in DC is the Van Ness location for Guapo's (which incidentally makes the best Tex-Mex I have had in the District).
Again, this is not great food, but it's not going to offend you either. It is slightly overpriced, but you live (or are looking for places) in DC. This should not surprise you. Recommended if Belga Cafe and Matchbox are completely filled and you are looking for a drink....
Pros: decent margs and prices
Cons: can get crowded on the patio