We got tickets to The Mattress Factory as a gift, so when we were in Pittsburgh we made it a priority. We actually enjoyed it a lot more than expected. The installations at the time were really interesting, especially the work of Yayoi Kusama (the polka dots). It was a fun hour or so out, but I don't really think it's worth the admission price. It's quite expensive for the size of the place and the amount of exhibits. I did notice they offer discounts on certain days and to students etc, so it's worth checking out if you are eligible.