Pittsburgh, for its size, has a fair amount of Indian restaurants and I would suggest that this one is the best in town serving Northern Indian cuisine.
Tamarind does have a nice atmosphere and it is located in a restored older house that has been remodeled in such a way that it provides a comfortable and warm ambiance. The servers were attentive, knowledgeable, professional, and nice.
Entrees are moderately priced for comparable meals at other Indian restaurants in the area. Regular entrees include a good portion of the main curry with rice and either dal (it is yellow dal in a soupy form--very good) or mixed vegetables on the side. One great aspect of Tamarind's menu is that they have Northern and Southern Indian cuisine offered, which is not terribly common in this region of the US.
Once again, I am sorry that there is not a half-star rating on yelp because I think that Tamarind is really between 4 and 5 stars. Tamarind would be a great place to take out of towners, go out with friends, or even go on a first date.