Truly superb tacos, guac (build your own) and Margaritas -- possibly the best I've ever had in all three categories. Even the house-made tortilla chips were extra crunchy & flavorful, without being at all greasy.
The vibe here is very hip, and the service is attentive and helpful. Even the bathroom is cool.
I found myself at tako two nights in a row, and although I was warned that it would be very crowded, the turnover at the inside bar was fast enough that I only waited maybe ten minutes to get a seat. That's entirely reasonable IMHO. I tried the steak tacos (Bistec) and the grilled chicken/avocado tacos on the two successive nights. I suppose if I was super picky I might have said the beef was a bit too rare for my tastes (they don't ask you about cooking temp), but the flavor was amazing. I actually liked the chicken even better. This place knows how to inject a lot of meaty flavor into their grilled items. This is one thing that makes the tacos truly exceptional. Background music is downtempo, hip, EDM genre, which seems to fit with the decor and the clientele quite well. This is the best food I have eaten in Pittsburgh. Highly recommended.