I've been to a few different Margaritavilles around the country and this one is by far my favorite (some of the others are actually rather mediocre). It's always busy (AKA festive) and a great time. My favorite place to sit is up on the 3rd floor balcony overlooking the strip. As far as the food goes, I'd recommend the nachos and the "cheeseburger in paradise." Food that I wouldn't quite recommend: Ahi tuna, crab/lobster dip (it was mostly cheese).
As expected, the margaritas are fantastic- just take a peak at the first page inside the menu and you can see all their signature creations. Mmmmm.