It's true when they say that the Oasis has 6300 guests but doesn't feel crowded, but in creating that atmosphere they seem to make a lot of sacrifices. They have everything and more that other ships have, but just about everything is smaller or lower quality. The zip line is a nice idea, but it only goes about 25 yards. There are two flow riders, but each is a lot smaller than those on other ships. Same with the internet centers and, most especially, the pools. Three pools, but none of which offers a good view of the band, and no big screen as on other ships (for that you have to go to the stadium seating aqua theater). With compartmentalized pools, the pool deck did not have that sweeping 'this is the place I want to hang out' feel. This was made even more so by moving all of the pool games and belly flop competition into the aqua theater, where you had to wait in line to sit in stadium seats in the sun.
The Good: The solarium and casino are far bigger and nicer than on other ships. Dividing the casino into smoking and non-smoking sides makes everyone comfortable. The donut shop is a great addition, and having central park on deck 8 makes for a nicer way to cut across the ship than walking through stateroom hallways.
The Bad: The service on this ship was indifferent at best, trending towards rude. With so many guests, they apparently do not have to put much effort. The boardwalk is a waste of space, except for the donut shop and except for the fact that it may draw some of the young children away from the other areas.
Overall: I would sail on this ship again if I had a compelling reason, but for the most part I think people are far better off sticking with the Freedom class vessels.