We booked this tour direct wit Circle Line rather that using NY passes, its worth doing this as it takes you front of line for the boat and priority seating on the upper deck.
It was probably the best value things we did in NY and well worth the money. The tour showed us a different perspective of all the sights and some we wouldn't have seen. Mike was a great tour guide, lots of information delivered by someone who clearly enjoys what he does.
Book this tour but be prepared it can get very cold in December on the river.