I am not a history buff or even a "Pitsburgh buff" but this museum was amazing! I went with my parents (from Michigan) on a random Sunday and we had a great time! There is such a wide variety of exhibits and I learned so much.
Pro tip: Leave more than 3 hours - there are like 6 floors to the museum all of which take a significant amount of time if you want to see everything. Also, they have student discounts and AAA discounts!