Went there recently for a class project that had to do with photographing art pieces...
We stayed (myself and my project partner included) untill closing time, wandering through all the exibits open to the public (There are some that are currently closed due to remodeling, the costumes and textiles exibits included)
We took plenty of pictures, wandered through everything we could, and several times ended up in exibits that were completly alone and devoid of people. We didn't see, hear, or notice anything out of the ordinary...but it did feel like someone was constantly watching you, even in the lonely exibits.
Aside from that...no ghost appeared...