it really depends on your pace, but the 2nd floor was the only exhibit open when I went, 3rd floor was being updated. and it was very brief, maybe a total of 40 pieces, in two large rooms.
Depends on when you go. I live in NYC and took a few friends a week ago. They paid money to go in and find out that at least 50% of the place was closed to the public for an installation. This was NOT readily disclosed beforehand. Needless to say, all were very unhappy. That said, if you go when the full extent of this lovely museum is available to view, it is a must-see. Even then, because it is small, 90 minutes should be sufficient. Well worth it! GO!
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