Let me echo the sentiment of other reviewers: Papusas. Delicious, greasy, and cheesy -- filled with either cheese and beans (for the standard papusa) or with your choice of meats for the deluxe papusa. Then you slather it with a pepper, carrot, and cabbage mixture, and then some sort of red sauce. Divine.
I know my boyfriend and I have ordered other things here (and they were alright), but this is the one menu item that keeps us coming back. That, and it's proximity to UNLV, is what give the this restaurant 4 stars in my book.
As others have commented, you do need to bring cash. Luckily there's a bank in the same parking lot if you need to leave your boyfriend at the counter and run to get cash (not that I've needed to do that or anything).
Be aware of the potential for a language barrier if you do not speak Spanish.
Finally, the restaurant can be LOUD. I've only been there once when the jukebox hasn't been so loud as to make normal conversation difficult.