I've read books in this style before, using letters, e-mails, texts and other communications.  I find that although it's interesting, it can be disjointed and distracting.  I found it difficult to get a good feel for the characters so there wasn't as much connection as I'd have liked.  The concept is original and appealing, I really liked the build up and tension, but overall it was a bit of a slog for me.