Took my son on this trip for his 15th birthday present, He loved it!!
My wife and I had an AMAZING flight.
The operation at Liberty is tightly run and orderly. You will have to wait about an hour for your flight even if you turn up on time...but that only adds to the excitment really.
This is the ONLY way to see NYC. every time we heard or saw a chopper for the rest of the week it made us laugh all over again.
Trip was 20 mins as described, and the pilot simply points out the buildings and sights - no real explanation but you'll be too busy looking in a hundred directions to worry about it.
Do it!
Great way to see the city. You get fantastic pictures you cant get anywhere else. Really lets you appreciate the vast size of Manhatten. Would reccommend this at start of your stay, gives you good ideas of locations for all the attractions. Only one small issue: make sure you take water or something with you in case of any delays. The air conditioning is non existent and we had to wait 2 hours for our flight as the president was in town! Guess delays dont happen that often but be prepared!