We have sailed with RCCL before but never on an Oasis class ship. I must say, whoever designed this ship is a genius. The ship was amazing, and even though there are around 6,000 people on board, it only once felt crowded. I'll start from the beginning:
Embarkation - as expected with this many people, getting through the line at security in the terminal took a while. However, once through security, the check-in was quick and easy.
Ship - Incredible!!! Very clean and well designed. I did not notice it to be any more crowded (and sometimes less) than other cruises I have been on. Central Park is amazing.
Embarkation Port
Labadee is truly amazing. In the past we have done the zip line. Although expensive, it is really worth it. Beaches are clean. The local drink, the Labadoozy, is recommended.
Not a big fan of Jamaica. In the past we did Dunns River Falls, because if you go to Jamaica, you go to the falls. It was a long drive, but the falls were actually a lot of fun. Many of the shore excursions require a long bus ride since almost everything to do is not in Falmouth.