I've seen her before and after the exhibit renovation. It's definitely something to see! The last time I was there a year or two ago I bought all my tickets the day I visited. So the U boat is extra but well worth it. As for a tour of the boat, it's guided and kinda short.

I think the reason you can't take pictures inside the sub is so you don't slow down the tour. Also the Aft Torpedo Room, Conning Tower, and I believe the Bow Torpedo Room are inaccessible. But I still highly recommend seeing it.