I really enjoyed it. Everything was very well organized and the train accommodations were quite nice. The cars were not crowded so we had plenty of room to sit and move from side-to-side to see everything. I was on Maasdam (1'200pax) so it may be more crowded if you are on a monster ship. Every car has an open (sides are open for air but covered to protect from rain) top area and the lower deck is enclosed and air conditioned. They provided free drinks (alcoholic and virgin) and snacks. Each car also has a restroom.
The train slowly works its way around half the island. You get to see: sugar cane fields, into peoples back yards, beaches, moutains... The narrator is informative but can get a bit repetitive after a couple hours. The bus ride back to the pier was your usual tourist bus ride.