The Bellagio is still my favorite buffet in town, but the Wynn is good too, in different ways. It has less to offer but makes up for it with quality of selection and visual display.
I love to come here for breakfast.. they have the most delicious chocolate croissants! I eat several which already makes up the price for the meal. The meusli is wonderful too with lots of fresh fruit and berries to garnish.
If you come late enough you can catch some of the lunch offerings.. but stay away from the Kobe meatballs. The congee (rice porridge) isn't that good either (if you're asian). I don't really think the lunch is worth $20. Dinner is pretty good, but for the price I'd rather go over to the Bellagio which always offers a tasty Chilean Sea Bass as well as lamb and prime rib and crab legs, etc.
The ambience of the room is serene with lots of garden motifs and the staff have always been pleasant and friendly everytime I eat here. For the quality of food and service the prices are very reasonable ($15 for breakfast).