Feast Buffet is pretty decent. We have had a couple of bad experiences, but not from the food. There was a horrible line issue once, and the servers are sometimes slow to refills on drinks, clearing plates, etc.
The Red Rock PP card is the way to go if you are going to eat here. The prices are pretty reasonable. The Saturday breakfast is nice, and the Sunday buffets are a treat. It is also awesome getting the B1G1 coupons in the mail.
We have been other times to eat, but not for the Friday or Saturday night Seafood/Prime Rib buffets. The selection of food is always good. There is change of items, but the favorites always remain.
I wish the kids buffet price was a little bit cheaper. We have a small child who can be a picky eater, so it is often not a good value for him to eat.
Overall, the Feast Buffet in Red Rock is a great choice and value for the people of Summerlin. It is always busy when we're there.