I absolutely love 1900.
As a frequent flyer of all cheap Mexican restaurants I was a little hesitant at the $9.00 margaritas. However considering the couple of entrees that I have had, the chips and salsa, and their rather large (and intimidating) tequila list....it is definitely worth it.
We've been a couple of times and I've had the taco salads, enchiladas, and chimichangas. Holy chimichanga. It was incredible. They put some kind of homemade cheese sauce on it that I would probably bathe in given the chance.
Also, if he is in ask to sit in Oscar's section. He knows everything there is to know about their drink menu, including the best and the interesting. We met him one night when we came in on a Tuesday at 9ish (they close at 10). While we broke the cardinal rule of week night dining Oscar did not make us feel rushed at all. He told us to take our time and chatted it up with us until we were finished.
He even gave us the secrets to getting a good table there for Cinco de Mayo...which I will not be sharing.
I definitely recommend this place and plan on going back regularly. The food amazing, drinks delish, and chips and salsa some of the best I've had.