I agree. I've been there and absolutely loved going through it. Yes, they actually bring you into the sub, to view it from inside! The only un-authentic thing is that there are no "vaporous" cheeses and sausages slung from every available cranny, to get them through the long voyage until the "milch cow" sub re-fueled, and re-supplied them!
The torpedoes still stick in my mind. They are a wee bit bigger than they were in my adolescent imagination! Anyone visiting Chicago should see that... right after they visit the Futures exchanges... and get ripped on cabfare at least once!