I just returned from a 24-night Western and Eastern Mediterranean cruise on the Zuiderdam. I had sailed several times on Statendam-class ships, the Zaandam, Rotterdam and Amsterdam, but this was my first time on a Vista-class ship. On the basis of this cruise, I would have to say that the Vista ships have dumbed down some of the features that made Holland America unique.
The space previously occupied by the Explorations Cafe (Library/Internet Center) is now a fancy jewelry store and the Explorations Cafe has been banished to a section of the Crow's Nest on Deck 10. The book collection is intact and still good, but the computers, books and coffee bar are now squeezed into one smallish area. Between the noise from the coffee machine and the noise from the activities in the Crow's Nest, there is no longer a quiet place to read or work a puzzle.
Space is wasted on a strange dedicated Screening Room with only about 25 oversized leather chairs, instead of using the Culinary Center/Queens Lounge for movies. The number of seats in that lounge is also quite limited. There is a dark, gloomy nightclub Northern Lights that was virtually unoccupied during the entire cruise.
The GG cabin is a good deal if you want light but don't mind having your view obstructed by a lifeboat.