I enjoyed this museum so much that shortly after the visit, I became a member.
Just the Hall of Architecture alone is worth the visit. I don't believe that there is anywhere else in the world to see so many amazing plaster casts of architectural wonders.
Visit in the Christmas season to see amazing 20 feet tall trees themed to a current exhibit and the Neapolitan Presepio. It is a stunning manger scene that was constructed between 1700 and 1835 with amazing detail.
There is a good mix of time periods and styles and I love the chronology approach to the galleries. In fact, the only thing I don't enjoy is the Modern "Art". Mostly because many of the pieces look like something I could have created myself.
Overall, one of the better art museums I've been to and well worth a visit while you are in Pittsburgh.