My wife and I sailed on the May 21st sailing of the Celebrity Millennium in Europe. We flew from San Francisco and I'm 49 (13 cruises) and my wife is 55 and in wheelchair (5 cruises).
EMBARKATION: Smooth as it has ever been, but then we did get there kinda late (3:30) and the ship wasn't sailing from Venice until the next day so no hurry.
CABIN: Handicapped cabin #2022. Very nice with PLENTY of space, especially in the bathroom. Lots of drawers and shelves and comfortable beds with a small foldout couch and chair. Only drawback was opening of bathroom down would block access to part of the cabin by a wheelchair passenger. You would need to close the door to get by.