From what I've heard, the show is very much like PASSION in that the book and the score are intertwined in a way that is hard to tell where one ends and the other begins. It's not sung-through, but songs come out of dialogue and don't really have an "ending" in the typical sense. I haven't seen it but that's what I understand from my friends' comments.
I enjoyed the BWW.com preview.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"