MGM's Grand Buffet is really not that grand, after all. While it looks enormous, I found that a lot of the items on the buffet repeated as you went from aisle to aisle.
Food was average, as was the service. It was typical buffet far--roast beef, Jello, cakes, mayonnaise-y pasta/potato salads, fried chicken, etc.
We were there for lunch, so it may vary from dinner, but I doubt by much.
Well-placed slot machines near the buffet rang with winning pulls and made the customers itch to get out onto the casino floor.
If you're going to do a buffet while you're in Vegas, pass on this one and find another.