O is very impressive. The acrobatic acts they perform can be found in other cirque type shows but presentation of all that is what makes it cool.
What impressed me the most was the stage. The stage transforms from water to solid ground which I think is a technical achievement in itself.
I don't want to spoil any surprises... but let me say I was in awe from the moment the curtain lifted.
TIP: while front row seats sound good, with a show with so much going on (and a splsh zone), I recommend getting seats a couple of rows back.