Well worth it. I loved seeing the whole city from that high up. Definitely print your tickets out because they do not acccept phone vouchers. There is a fedex to print at the building but it takes time. Overall loved it.
The queue to get to the elevator to get to the deck takes over an hour and when you get up there you have to queue to get back down as well.
Didn't manage to go on this tour due to bad weather but later we booked dinner two levels down in the restaurant. The view is breathtaking definitely recommend a visit!