The Aviation Museum was pretty cool. It's not real big but you can get right close up and touch the aircraft. Make sure and go back to the hanger behind the museum to see the original bullet holes in the windows and door from the attack on Pearl Harbor. They also have different types of aircraft in this hanger.
If you're short on time at Pearl Harbor I would recommend seeing the other sites there first as I think they are more interesting and definitely more historical, but if you have time, the Aviation Museum is worth a visit.