I make a point of not eating Mexican food in Vegas (my high-maintenance taste buds only accept Mexican food in LA or Houston), but when I do, this is the spot. Although I'm not a fan of their chile relleno (which defines all of my Mexican dining experiences), I am having an explicit affair with their Carne Asada Super Nachos. It blows my mind every time, and I find myself thinking about it late at night while I'm in bed. To me, it's just that good. It sets me back $6.95, but it's worth it every time.
I think customer service is good here. It gets real busy at night though, so I usually take my order to go for a more intimate encounter with my beloved nachos.
I wouldn't recommend this place for dates, but it's a great place to head over to after several rounds of drinks. However, they close at midnight so make sure you have a designated driver pick up your food while you down your last couple of beers/body shots/whatever.