The National September 11 Memorial and Museum is indeed ambitious and moving, although I've seen most of the material elsewhere (especially the Newseum in Washington). There is a large inner sanctum with many small items, especially from the Pentagon, where photography is not permitted. Flash is prohibited in most of the museum, which could present a practical problem for most picture taking, but the store sells a National Geographic book with pictures of absolutely everything.
The directions fail to mention that the R train does not stop at Rector St.on nights and weekends, no doubt the cause of many late arrivals, which puts the visitor in a holding line with further delays getting in. Take the #1 train if possible.
The visit is one log descent, and is quite moving, The film "The Rise of Al Qaeda" with Brian Williams is shown.
I'm told that elevator visits to the top of the Freedom Tower will be possible by summer of 2015.