We came to the 7 PM show on a Monday night, and the place was half-full. The show started a few minutes late. Once it got going, though, it was a pretty nice show.
The theater itself was nice and intimate, with seating all round the stage. We sat in the 6th row, but honestly, there isn't a bad seat in the house. The lighting, music, and performers were incredible. I have not seen any other Cirque-type shows, so I can't compare (the gf liked O better), but I would definitely recmmend checking out Le Reve at the Wynn if you get the chance.