I've been known to voice reservations about book trailers. (I seem to voice reservations about most things.) I've also read that publishing people wonder if they sell books.
I find a lot of book trailers a bit amateurish and...sloooooow. Often times I could read a couple of paragraphs and get some real info on a book in the time it takes to get through some of these things that don't do much more than try to create atmosphere. I don't have time for atmosphere! Life is short, people!
Last month (Yeah, yeah, yeah, I'm always behind.) The Spectacle ran a post on book trailers that included three examples. I liked The Adoration of Jenna Fox very much, but I don't know if that trailer would have hooked me. It's an example of what I meant by slow. I doubt I would have sat through it if I hadn't already read the book. The Nightmare Academy trailer seemed generic to me. It seemed as if it was just promoting another scary story.
The trailer for Shiver, though--How beautiful. It didn't really tell me much, but it's so stunning that I watched it a couple of times, and I went to the author's website to see what was going on with that story. And now I am interested, and I do want to get hold of that book.
So while the trailer doesn't communicate a whole lot (which I think a trailer really ought to do), it still worked because it is, as Parker Peevyhouse said at The Spectacle, a work of art. Not many people are going to be able to pull that off, but Maggie Stiefvater who wrote Shiver and made her own trailer, did.