This was my first Cirque Du Soleil show so I didn't know what to expect or how to compare it to the other shows, but it was AMAZING!! Since then I've also seen Le Reve and don't think it's as good as O.
This show is very acrobatics focused. There is no story but every scene is is like a tiny story, if you will. I really liked the live singers in the booth on the right side of the stage, and the clown scenes were pretty funny too.
Some parts of the show were kind of creepy/weird but still very cool; like one of those real circuses. There was always so much going on I wish I could watch everything at once, but there are just too many people doing too many different things at once. I guess it is part of the overall effect, though.
There are a couple of surprising scenes involving "audience interactions", but I won't spoil it for you. The way they open and close the curtains was very innovative and unexpected and fit very well with the whole show.
Overall I would definitely come again!! So worth the money!
TIP: find seats near the middle/upper sections. You'll be able to see everything going on on stage and won't have to crane your neck to see the first performer descend from the ceiling!