My husband and I just attended his sisters wedding along with 20 or so other guests in April this year. It was on RC Adventure of the Seas, this was a massive and beautiful ship. We were treated like royalty and everything with the wedding went well. She was given a time of 12 noon for her wedding and that changed to 3pm at some point which was better. The wedding was in the chapel on board as we were ported in St Maarten. We had time after the wedding to leave the ship to take pics nearby but couldn't go far due to sail time.
I would recocommend this type of wedding to anyone. Royal Caribbean was fantastic.