I have only been on one cruise (Royal Caribbean cruise around Western Europe). It was a great experience because I was able to visit a bunch of places in a short period of time.
If you are able to, I would advise that you book some excursions since sometimes you are at a port for only a few hours. That way, you are making the most of your time there.
On the cruise, there are a lot of activities and free food so there is always plenty to do. For the cabin, I really recommend getting a balcony view. It was so nice to sit outside with a coffee and watch the sea (and wave at the people on other cruise ships when you pass them!).
I also noticed that prices for cruises go down significantly right before they are set to leave since they are trying to fill up empty spots.
Hope this helps.