I cannot comment about other cruises but on this cruise, because of the size of the ship and the port facilities of the respective cities, the ship did not always dock in a walkable area. This meant needing to purchase a bus transfer into the city. Not a big deal. The cost was usually around 6 euro each way and they ran quite frequently.
You wouldn't believe the number of times I heard people complaining about how "far" the ship was and how long the drive was (15 - 25 min)! Maybe they had the romantic idea that we were supposed to dock right in the middle of town within a few steps to the best restaurant or something?
I happen to like looking around at the different port facilities. For example in Gothenburg or Goteburg, they are a serious shipping port and I find it neat to see numerous large freighters and tugs and cranes at work. These port cities weren't created just for cruise ship travellers!
The 2 ports of Copenhagen and Tallin didn't require transfers as both were within a 30 min walk into town. The walk into Tallin wasn't as nice looking or intuitive as Copenhagen but was clean and safe.
The maps you get from the ship aren't very good. Not all the streets are labelled so you do have to figure things out on your own or better yet, bring your own maps for a less frustrating experience.
I do wonder if the maps are done that way to encourage the purchase of excursions and tours from the ship. There is big money to be made. At an average cost of $40 a person for each port for the most basic of tours right up to $180, a family of four taking all the excursions for each stop will cost a bundle.
Judging from the number of tour buses waiting to meet the ship each stop, I can just imagine how much money is made. And I haven't even started on the amount of alcohol that I saw people drinking on board.