At $110 for seats, "O" had better offer more than a few pretty faces wearing headresses. Cirque du Soleil's circus-ballet raised the bar on entertainment, to put it mildly. What can you say about a stage filled with 1.5 million gallons of water and a cast that buoys in and out of it with the precision of a surgical team? Through Dali-esque settings and feats fitting of Chinese acrobats, it's an ooh-and-ahh evening that is, most of all, beautiful to watch and haunting to hear. The play on words -- from Oh!, to eau, to the O that is being and nothingness -- shows its twists and turns through dazzling stage settings and costumes. Characters appear and disappear, drown and pop up, and fall and fly, all with the greatest of poetry. A circus for the senses here happening twice nightly (except Wednesdays and Thursdays).