My wife and I cruised the Southern Caribbean aboard Summit over Easter weekend 2008. This was our fourth cruise overall, and third with Celebrity. Overall we were very satisfied with our cruise. This was a last-minute decision for us - we booked the cruise less than 3 weeks before the sailing. We got a GREAT deal online (maybe because it was so last-minute) and much better than any deal we've gotten from travel agents we've used in the past.
We booked a "stateroom guarantee" (thinking we would get an upgrade from Celebrity later) which in retrospect we would not do again. Apparently the days of guarantees & automatic upgrades are things of the past. Because we did not get to choose the cabin, it was picked for us by Celebrity, upgrades were not given or offered, and our stateroom #2181 was near the back of the ship and the crew entrances. After booking, we discovered that if we had picked the cabin # at booking time, we could have gotten one deck higher (3rd) and chosen a cabin closer to midship, for the same price. It's all a learning process, we have discovered.
Embarkation and disembarkation were a breeze. The only line we waited in was the line at Customs at the end, and even that was only 5-10 minutes.