We went here for free thanks to MyVegas/Mlife. It's probably one of the better "cheap buffet" options. "Cheap" in price compared to the big names anyways (Bellagio, Caesars, Wynn, etc). Plenty of food options, food seemed to always be fresh, and the desserts were great. If you want ambience / premier service, go to Bellagio or the Wynn, but if you just want endless food for a decent price (or free if you're like us), the Mirage buffet is just fine.
We had no wait for lunch entry at 2:30pm on a Sunday. When we left, during dinner entry (around 3:45) there still wasn't much of a line.