This pass was well worth buying. It contains tickets for everything you want to visit in NY, and saved us a lot in time and money. We collected the book from the first sight we visited (Rockefeller centre), and it was very easy. Would highly recommend.
The Empire State Building was great and definately worth the return at night, after 10pm. The Met was very interesting but you need a day to do this, if you have the time. Recommend coffee on the roof terrace with great views over the tops of the trees in Central Park. Walked through Central Park to the Natural History Museum, again could be all day. Whales exhibition at this time well worth it. The Guggenhiem was a great disappointment as the present installation covers the entire central atrium with white fabric, giving a view of changing colours from the bottom only. Having visited before and seen the amaising structure of the building, been able to look down from the roof and look down to the fish eye pond. What a let down. Make sure you check what exhibitions are being shown at the museums before you visit. We paid for the Top of the Rock which was even more fantastic than the ESB. The views over most of the island gave a much better idea of the Big Apple. Overall by this from home for the best deal.
Visits to Empire State Building, Rockafeller Centre, the Museums and the Statue of Liberty are a must when visiting New York.