This place is absolutely fantastic - I live in the building upstairs so it's super convenient for me, but the delivery is appropriately speedy.
The food is amazing, they're smart enough to recognize (as many Mexican restaurants don't) that you need to put some of the wet stuff (e.g. guac, pico, sour cream) on the side for delivery so the food never comes soggy and always tastes fresh.
As for what to order - the mini-Chimichangas are great, have never seen this option before but it's satisfying when split between 2 people (you get two in one order). The Chicken Mole burrito is one of the better burritos I've ever had, I get it here every time I order. Nachos are awesome too. Highly recommend this place, in a city with a dearth of Mexican options the food is consistently good and the service is reliable and friendly.