My brother dragged me to the Wynn buffet and I'm afraid I have to echo the conventional wisdom: both my brother (who lives for buffets) and I (a confirmed buffetophobe) were slightly disappointed.
The selections are slightly more limited than, say, Bellagio's or Aladdin's. Not as much exotica is offered as Bellagio's. And the execution, particularly of the cooked meats and fish, wasn't deft. Several of the fish and foul dishes looked promising but in each case, the proeins were overcooked. Rack of lamb was mushy but the marinated flank steak was tasty.
By far my favorite dish was roasted asparagus and the other cooked vegetables still had life in them (the salad offerings looked uninspired, so I didn't try any of them). Peeled shrimp were OK but crab legs were the usual watery buffet specimens. I've seen other reviews criticize the desserts, and although the selection was much smaller than the top buffets, I thought the quality wasn't bad.
Service was excellent. We were seated in one of several small rooms. It was exceedingly pleasant and quiet there, although, inexplicably, those seated against the wall are plopped on benches with wooden horizontal strips against their back: uncomfortable at best. Cutlery and dishes were the nicest I've ever seen at a "regular" buffet in Las Vegas. Full bar service is available and Wynn offers Coca-Cola products, a rarity in a Pepsi town.