Oslo was truly beautiful. We docked right next to the Opera house and went on a tour of the resistance museum and Akershus Castle for a total of $60 per person. It was very good, and our tour guide was a historian. It was a very good tour, would recommend it. The ship docks with a short 15 minute walk into town where they have shopping.
We went to the Ice Bar and Rosenberg Castle. It was a pretty nice tour, but the ice bar was over rated, and in general I was not a fan of Copenhagen and their politics. However Copenhagen is a very nice city, and it had some very nice sights.
Visby is simply beautiful. We took the West Coast Highlights tour, where we saw a Church, and old fishing town, and a panoramic view of the bay. Also the city of Visby was simply beautiful, with cobblestone streets and nice shops in the old city. Kind of had a downtown feel to it. Unfortunately we were there when everything was closed for Midsummer holiday, but it was still beautiful to see. I did shatter my Iphone on the Cobblestones there though, but can't really blame that on the destination.
Russia has it's pluses and minuses. First of all you can't get off the boat without a tour or a visa. My reason for giving it a 5 not a 5+. We took a Hermitage and St. Petersburg highlights tour the first day. This was a very good tour and our tour guide was a Art History major, so that was helpful going through the Hermitage museum. Overall however, St. Petersburg is a very depressing place, which reeks of depressed people. It is definitely something to see, but I simply cannot define it as beautiful, because most of it isn't. Also keep in mind the bridges go up from 1:30am to 4:30am making it very difficult to get back to where the boat is docked. We also took a Moscow and the Mysterious Kremlin tour where we took a flight to Moscow and back. It was overall a good flight, and we had a great time. Moscow was simply amazing, and we took a tour of the Kremlin castles, which were visually stunning, with Gold and Marble nearly everywhere. This tour was apparently really hard to get and very few people get to see it. We ate dinner at the Writer's Club which is definitely a highlight, you can still smoke inside however most cruise guests are very closed-minded so don't expect to be socially accepted doing it. They do have a smoking room where Ronald Reagan once sat. The food and service was extremely good there. We barely made it back before the bridges opened and we would be stuck. The last day we did a Constantine palace tour, which included a wine tasting. It was a beautiful tour, that left you in awe of the Russian architecture. Also our sommelier at the wine tasting was the same sommelier that served George Bush and Putin in the same place where we had our wine tasting. Amazing simply amazing.
Personally I wasn't a fan of Helsinki, quite frankly it was kind of boring. It was just generally very boring, and we took a bus tour, which showed us the sites. The architecture was boring, everything was just kind of boring.
We took a bus and boat tour in Stockholm, and were content with it. We went exploring through Stockholm ourselves, and had a wonderful time. The buses from the boat drop you off right downtown and it is up to you to explore on your own. It is a very nice and clean city, and I would recommend exploring it, as you will likely enjoy it.