One word: pupusas.
The pupusas here are amazing. It's across the street from UNLV so I frequent here after classes or during my gaps. The convenience of this location is great. I've never eaten anything here other than the pupusas so I can't speak for any other foods, but this place seems extremely authentic.
I have seen other reviews talking about language barriers with the staff here. I have never really had that problem, so service has never really been an issue for me. The only negative downside I would say is that you need to bring cash to this place.