I absolutely love this show. It is a toss up between Mystere & "O". If you want more for your buck though... watch Mystere. It is actually quite cheaper than "O". It is comical, and incredibly entertaining.
You don't want to be too close to the stage for this show. So much is going on that you would have to go back and forth the whole time. I recommend mid level seats. Infact, the far back seats would be better than the very front row. Also, much of the performance takes place dangling from the ceiling. You would have to strain your neck to see it all.
The comedic/ intermission actors love to single out crowd members to embarrass (especially the front row). One of the best parts for me is the full grown, 'large' man in a diaper acting like a baby. (If you speak or understand french, the baby will be even funnier to you).
This is actually one of the older Cirque show (compared to most of the others), and I personally think that it is one of the best too. The lighting, the costumes, and the music feels old school cirque. None of this "Cris Angel no magic" nonsense.
Make sure to call for specials, because the ticketbooth will sometimes not volunteer the information unless you ask. There are always good deals for locals too.