I enjoyed this cruise so much! It was not the "party" atmosphere like your typical Caribbean cruises can be, it was much more informal and relaxed. We had a naturalist giving nature talks during the cruise, and a couple of days, park rangers boarded the ship to cruise with us for a bit. The scenery was spectacular, but you really needed to go on shore excursions (hikes, kayaking, whale-watching, train rides, etc.) to make the most of it. Don't you dare forget your camera! We saw both humpback and orca whales, very awesome. The weather is unpredictable and you definitely need to pack layers and bring shoes that can stand getting wet. We were blessed with beautiful sunny weather each day (although it was cold when we were near the glacier), however it is my understanding that passengers are not that fortunate on most Alaskan cruises!
As for the ship, the food was very good, the room was identical to 3 other Carnival ships that I've sailed on, everything was clean, ship employees were polite and helpful, then entertainment was better than most past cruises -- all in all a great time! Do not hesitate to book this cruise, especially at the end of the season where you can go to Glacier Bay...and everything is on sale in the ports!