Does not honor reservations. I reserved a City Penthouse suite weeks in advance and literally less than 36 hours before our trip they called to tell me that they yanked my suite out from under me. Their "suite utilization committee" had gone over their suite availability and decided that they needed mine, so tough you know what for me. I said "so, apparently a reservation doesn't mean a reservation" and they said "it means you have reserved A room not any PARTICULAR room." They then proceeded to tell me they would be happy to do me the favor of "allowing" me to book a lesser room. And they couldn't care less about how unhappy I was. And this was with the Mlife tier benefits and all. Imagine how they treat regular folks.
I slammed the phone down, pulled up the Four Seasons site and booked my suite there in about one minute. They treat you like gold, and if they screw up they act like it's THEIR fault, not yours.
Book MGM Grand Las Vegas only if you hate yourself and you don't mind wondering if you'll actually get your room or not.