We had just walked along The High Line and saw that this was at the end of the route and decided to go up as we were there anyway. There was no queue and we got timed entry tickets for 2 minutes after we got there, and were in about 5 minutes later.
Personally I didn't like the first part as it's made to feel like you're underground and I felt quite claustrophobic in that section (between security and the lift up) so I didn't get to read any of the signs / info on the boards as I was just trying to get out of that section (made slower by people blocking the way taking photos).
I'm not sure the lift took even two minutes to get to the top of the building once as it was very quick, but you are all quite squashed in. They have moving images on the sides of the lift but you can't see them. Once you're out at the top it's a very spacious and bright room / floor. There's a shop and there were a few food carts selling snacks, alcohol, and waffles. However there's barely any seating so whilst we would have appreciated a hot chocolate and a sit down, we didn't bother as we would have had to have stood up the whole time and we'd just been walking for miles!
Outside was not as cold / windy as I expected considering how cold it was on street level - I assume the glass windows are quite protective.
People were making an orderly queue to stand in the corner where the 2 window-walls meet which was nice as these things are normally just unorganised scrums in other places!
The windows were pretty smeary in places (fingerprints and weather conditions, I assume) so photos wouldn't look great in them.
When we went, due to the weather, the stairs outside and the glass floor were blocked off which was a shame but I'd rather they be safe about these things.
There was a restaurant on the level above but it looked quite fancy so we didn't go in (I was looking for more casual food, definitely not in a fancy mood food!)
Weirdly on the same floor as the restaurant were two lifts that people were being directed to use to go down rather than queueing in the normal exit line with the rest of the people waiting to go down, which seemed an odd way of doing things. The queue wasn't too big and didn't us long to get down.
When you get back downstairs they try and sell you the photo package of the green screen photo they took of you on your way up. Prices are not clear and are very expensive when you do find them out!