Provided you're at least a casual Jimmy Buffett fan, this restaurant is fun. One of the cheaper meals out I had on the strip. The food was quite good, and the service was more than adequate. The atmosphere is clearly what makes or breaks this restaurant for most people.
The giant volcano over the main bar of course pales in comparison to the one in front of the Mirage just down the street, but it's purposefully more kitschy and fun. There's a giant "Booze in the Blender" that slowly fills up over an hour and when it does, the "Volcano blows." Most of the floor is decorated to look like you're in open water and several of the tables are decorated like skiffs. We were seated close to the bar on the main 'ship' section of the restaurant. There were several "Postcards from the Road" screens showing a combination of Jimmy Buffett videos and other music from his Sirius XM station. I don't follow Buffett personally but have always been a casual fan. His style of music is fitting for the very very casual atmosphere of the restaurant.
Just like most musician-themed bar/restaurants, most of the items on the menu are named after forced puns on Buffett songs. This seems to work a little better with Buffett since he actually already has both his own beer and margarita line and songs about food.
I was tempted to get the "Cheeseburger in Paradise" but instead went with the "Volcano Burger." It had chili and cheese sauce and avocado and Fritos and jalapenos and it was a little overwhelming. The burger kind of fell apart when I tried to eat it. Nevertheless it was tasty and cooked to my liking. The bun was a little dry but not too bad. We went in the afternoon for lunch and did not have to wait long. The burger may have benefited from having the bun scooped out to leave more room for all of the toppings. On the bright side, I had plenty of chili/meat salad to eat after I was finished with my burger from all the toppings that fell off.
Long story short: Margaritaville is not about the food. It's clearly about spending some time wishing you could ever be as relaxed and carefree as Jimmy Buffett himself. The atmosphere is nice and the food is fine. If you're a Buffett fan you'll have the time of your life, as long as you don't blow out your flip flop.