We took the Passport to Central America cruise in May, 2008 on the MV Explorer. This was an enrichment voyage run by the Institute for Shipboard Education (Semester at Sea). We have taken many cruises from Carnival and MSC.
The voyage embarked out of Nassau, Bahamas. The port is very disorganized, hot, and the taxis are expensive. The crew and staff on the ship are also disorganized. They try to take part of their regular staff and create shorter cruises to fill in between their regular semester cruises. The disorganization really shows.
The ship is OK for a small cruise ship. The library and internet access are probably the best things on board. Cabins seem to be regular size, but the beds are the worst we have encountered.
We were very disappointed with the food and service. It was very bland, just like you would expect from a college cafeteria. For the evening meals in the main dining room, they offered table service. They hired additional waiters for these cruises, and it was disorganized. Service was extremely slow - usually about an hour wait for the main course. They had 2 BBQ's, which were sort of like a picnic BBQ at the pool area. These turned out to be the best meals of the entire cruise.
Entertainment was definitely not normal cruise quality. They had a barbershop quartet which was lacking in harmony. The focus of the cruise was supposed to be "enrichment" with sessions and expert speakers - college professors and such. They had one college professor who gave 2 lectures on ecology, and he was excellent. Otherwise, the sessions were very poor. They had art classes, but the room only held 18 people - not quite enough for the 50 or 60 people who were interested. They did offer free movies and documentaries on the cabin TV's, which were very good. I learned a lot about global warming and how the Panama Canal was built. However, these were only shown at certain times during the day - you could not watch them when you wanted.
They offered a "Field Program" which turned out to be regular cruise tours at the various ports. However, they sent representatives from the ship to monitor these. One of the representatives cut short the tour and had the tour guide return to the ship without covering all of the tour highlights. The reason was that we could not be late. They did allow booze to be brought on board from the various ports.
All in all, the crew and staff treated us more or less like college students. I have had better food in some college cafeterias. We were very disappointed with some of the ship representatives on the tours. We complained but received no satisfaction. We really love to cruise, and this is the first cruise we have been on that I would not go on again.