This museum is good for people who ordinarily get bored at museums.
It's loaded with history, but the vibrant, eye-catching and exciting kind. There are 7 floors, packed with a variety of works, so chances are good there's something for everyone. (Although some content is a bit inappropriate for kids.)
We went on a Sunday, and it was slow but not dead. Everybody there had a chance to peruse what they wanted to without feeling rushed. I prefer this, because you can linger if a particular piece speaks to you.
A total bonus: If you are a geek about museum gift shops (Guilty!), this one has some unique and quirky offerings, though the prices are... museum gift shop-y.
All in all, this is a Pittsburgh must-see!