This museum was very good! The staff working at the time I went did not speak English, (I don't ever expect them to since it is Japan after all) but they do provide you with an English walk through handout that coordinates with numbers next to the exhibits. That way you can look up what everything is and get a brief description, which I found very helpful.
There was several floors of exhibits and towards the end there is an interactive simulation that you can try and steer a ship into Sasebo Bay lol. I couldn't initially figure it out but a gentleman that works there was very friendly and showed me what to do with out me having to ask for any help.
The gift shop had many good souvenirs from miniature models to keychains.