Haynes manual
I've got a copy of the Haynes manual and I have to say that I thought it was a really good guide to the Raspberry PI. Like most of the other Haynes manuals, it gives excellent step by step information without making it sound as if they are treating you like an idiot.
If I were being a touch picky, I would suggest that they might have usefully added a little more information about programming the Pi; there is some detail in there along with sample code and it is very helfpul, but I felt that a few more samples from specific example projects to give the user some ideas on how they might use it would have been of real benefit.