If you like watching a performance while whispering "OMG" to yourself most of the time due to sheer amazement, this is for you! O is still one of my favorite Cirques and I watched it over 2 years ago. I did not get that great of seats (far left) but I swear I will watch it again.
All I could say is...holding your breath watching the performers perform death-defying stunts is a scary and thrilling experience. Add that with stunning visuals and a involving musical score for a very worthwhile and must-watch Cirque!
It's a little pricier than the other Cirques in Vegas, but I think it's worth it. I haven't heard any bad things about O, or met a person who didn't like it.