I am not even sure if they accept reservations, but our "20-minute wait" turned into an hour. That was fine, and it passed easily enough. The place was bustling! The food was worth the wait, and the prices were right (I think my combination plate of enchiladas was $7 and my sangria $5).
It was snowing outside, so we waited indoors by the fireplace.
Everything was delicious. I plan to eat here on every visit to Santa Fe.