What a cool place! We really didn't spend a lot of time here but for about an hour we explored as much as we could. If I were a student at Pitt, this is where I would hang out. It is literally a Cathedral of Learning. I know it doesn't sound super exciting, but you have to check this place out. DJ's review is solid and covers all the details about themes, architecture, etc.
The Heinz Memorial Chapel & the Stephen Foster Memorial are really cool as well and they are right there. Do it all if you have time!