We traveled as a group of 4 in our early 30s. For my husband and myself, it was our 4th cruise (2 Carnival, 1 RCI). All of us have been to Europe several times for land-based vacays.
I know I'm terribly late in posting this, but I figure that people are probably right now planning their Baltic cruises for this summer so it might still be useful. If you're just considering booking this cruise, DO IT! It's great.
The ship: The ship is nice. Well maintained and all that. Less gaudy than a Carnival ship but laid out similarly, which we like (except for the decks that you can't pass all the way through on, but it's not that big of a deal).