Bring that I'm from NM, I'll admit - I'm a little partial to Si Señor. However, that's only due to the fact that they nail the New Mexican food menu. Seeing as how they started out in Las Cruces, NM I'd expect nothing less than authentic New Mexican cuisine, and that's exactly what you get.
The service is usually pretty good, I'd say the only downside is it's basically impossible to place a phone order. I've tried placing a call-in order about 5 times and was only successful once. They're always busy, which s a good thing, but I feel as though it has to deter some business when you literally have to drive there and place your to-go order in person, then wait for it to be prepared.
All in all the food is excellent and worth waiting for, as our family comes here at least 2-3 times a month. Highly recommend their ground beef tacos, and enchilada-style (smothered) burritos. Kiddos usually enjoy a taco plate or bean and cheese burrito. Last, their sopapillas are a heavenly ending to your meal - pro tip: get the cinnamon and sugar ones all day everyday.