I was a regular of Roberto's in the early 2000's when I first lived in Vegas. After having moved all over most of the Southwest, I could not wait to return to Roberto's when I decided on moving back to Vegas. The flavor of this cheap and easy Mexican venue is something that no other town or chain can replicate!
There are not many options for a full-course mexican meal at 3am, for a decent price. My only advice is early morning hours, they are rather slow. I will often stop in here on my way to work and load up for the day and the service isn't quite ready for prime time. Food quality is still good though!