Well, one problem with this that I've encountered is that often you have no way of knowing a book even exists unless you search NEI for it (and they're often titled with something other than book) or happen to find one as dungeon loot. Does make it a bit harder to get started when you have no idea the documentation exists or how to acquire it.I have to say this is one of the main reasons I like having in-game documentation, as the information there tends to be more reliable than from some other places, which may be wrong or just out-dated.
I do agree with RedBoss though, I wish books didn't spawn on you. Make the books craftable, using very basic stuff from the mod that can be found in NEI. That way, people that want it can have it and people who don't want the book or aren't bothered about the mod can ignore the book.
If anything start the player off with a single book containing a list of guidebooks/manuals/etc. from the different mods.
