I've seen 4 cirque du soleil shows.  I saw O late October 2011.  I just have to say I was expecting to be overwhelmed, as I am a huge fan of cirque du soleil.  I was disappointed.  The other 2 shows I saw were much better, The Beatles Love, and Zarkana, in Radio City Music Hall.  The other show I saw was a traveling show Banana Shpeel.  I just had heard \"O\" was the BEST, and was simply underwhelmed.  I wish we would have seen the new Elvis one instead, I guess on my next Vegas trip.