I think that if you watch the NCL videos posted on YouTube you can draw your own conclusions. With that said I stayed in the Haven which was fine, but once you leave that area it's a completely different experience. And unfortunately, you do have to go into the main part of the ship. Knowing what to expect I think you could have a good time. Just don't try to compare NCL to Crystal.
From your posts I gather you are somewhat of a foodie. On your return to Kotor you might want to have lunch at ( or at least research ) a wonderful restaurant called Stari Mlini. A short drive just outside of the city located in a lovely setting, it delivers wonderful local cuisine. email@example.com