We visited the One World Observatory on our 2nd visit to New York City. On our first visit we visted Top Of The Rock and the Empire State Building observation deck. This time around we opted for Summit One Vanderbuilt and the One World Observatory.
One World was the last of the 4 to be visited and it's because of this I've had to give it a rating of "average". If it's the only observation deck you visit you'll probably love it and have a great time, if you visit the others I suspect like me you might find it a little underwhelming.
The observation deck is split over 2 floors, but the 2nd floor is the restaurant / cafe area so it's unless you're dining, it's really just one floor. The observation floor is also pretty small, we walked around it and were suprised to find ourselves back where we started very quickly. The deck is obviously set up with floor to ceiling glass but is hampered quite severely by large thick frames spaced pretty close together which really do get in the way when you're taking photos with members of your party in them, but no problem if you're just taking a photo of the landscape. This is one of the key areas where it fails against its competitors, they simply offer better, less restictive photo opportunities.
There was an interesting looking circular array of LCD screens set up with a sign indictating a start of a show time. We sat and waited for it, a lady showed up and gave a 15 minute talk on NYC and the building, it was fairly interesting but the visual presentation was lacking and the ciruclar LCD set up seemed silly and would be better presented with just a single large screen.
On arrival you're offered the chance to pay $15 for a tablet device, it was included in our ticket. These are a total waste of time and ourselves and several others ditched them on a table within the first 5 - 10 mins. So if you're curious, don't bother paying, somebody will no doubt leave one for you to take a loot at.
In conclusion, One World offers decent landscape views and is the only deck in lower Manhatton. But it's pretty small, has somewhat restricted views, and no outside access which unfortunately puts it behind its competitors in our opinion.
I would reccomend Top Of The Rock for the best views overall (great shots of Empire State building and Central park) and Summit One for a unique mix of great outside photo ops with fun mind bending inside photo ops.