The food at some buffets is basically a glorified cafeteria experience while others it is a fine dining experience. The buffet at the M resort is on the higher end of the spectrum. First of all, this is the first time I've ever encountered an all-you-can-drink buffet. There's a decent selection of draft beers and wines and for $23 ($30 on weekends with seafood) you can get your money's worth in just liquid alone.
The food was very good, and I had to get a second helping of the prime rib it was so amazing. There are more food choices here then one person can reasonably try. Save room for dessert because there is a large selection of gelato and sorbet along with crepes, cakes, creme brûlée, flan and more.
Only negative things were the long ~20 minute line to get in and the poor acoustics inside. It's on the echoy loud side.