Visited this place a few days ago, in the midst of the big snow storm of 2016. Architecturally, it is a great building: I loved the ground floor in all its components, from the giant 'porch' on the outside which flawlessly continues inside and become the restaurant/cafè, bookstore (love the shelves) and finally the museum itself. Once upstairs, the cast expanse of rooms allows for the exhibition of large pieces that can be admired in all their grandeur from afar, like in the Frank Stella show.
I loved the terraces that allow for some of the best sights of downtown, not as high as other buildings but definitely higher and with a different point of view than the High Line.
What I found confusing was the seemingly little importance given to the communication between floors, which reminded me of the New Museum on the Bowery, The elevators, albeit capacious, are slow, and if I recall it correctly, do not each the eight floor. You get to the 6th and then if you want to go further up, you have to look for stairs (not obvious like in the Breuer's Whitney, but ensconced away). If you are able to get the 8th floor, you will be rewarded by extraordinary views of the city and a very pleasant (albeit a bit steep) restaurant. If then, among other things, you happen to cross path and sit next to, as we did, Renzo Piano himself, who was visiting the Stella exhibit like any common mortal, then you'll think you found your Graal at last.
PS if you wondered, I did not ask him why the stairs were so elusive..