We went on the Oasis in March 2011. It is an impressive ship but loses the feel of cruising as it is too big!
There are endless things to do and the shows are great but we found it too busy onboard to relax enough. Many many Brazilian tourists ready with their elbows and just general lack of manners meant the buffet in windjammer wasn't worth the hastle! Avoid if you can, there are plenty of other places to eat though.
The ice show and aqua theatre show are brilliant. The casino is large but is missing a couple more roulette tables when the Black Jacks were empty!
We had a balcony cabin which was nice but seemed narrower then the Liberty of the seas cabin.
Great food at the main dining room and good service
Our general feeling of the ship is it is a fantastic achievement from Royal Carribbean but it is a bit like Vegas at sea rather than a cruise, it also suffered from just being too busy!
Royal Carribean look after our age group really well (33) but this ship has too many people and young families onboard. We will go back to the Liberty size ship or smaller next time for a bit more sophistication!