We did this as one of the three things you could pick with our attraction tickets direct passes. The museum itself brought tears to my eyes, very emotional. The walking tour was great although I think our tour guide must have brought up at least 4 times that he didn't get paid to do the tour. This made me feel like I had to give him some sort of tip for the tour although we had already paid for the tour itself and given a generous donation to the museum itself.
Nevertheless, you have to pay your respects to 9/11 when in New York City and I'm really glad I did that.More