As far as I can tell, all the cornsnake books are dated. The old timers who write the books don't tend to adopt the latest techniques/equipment of the hobby (like t-stats). They give instruction on how they have always kept them, but that is not necessairly the current best advice to ensure sucess for a beginner.
That said, I still like books, and they are proof that there can be more than one way to keep these animals healthy.
Also, the internet may not always be accessible. Good to have another source.
Re. BP's, and care info, I would probably choose the Kevin McCurley (spell? of NERD) book - not the big new one on morphs, but the older, slimmer one. Amazon listed it, last time I looked. I don't have a BP yet, so I don't haven't bought that one yet.