I'm not too sure about this offer now... I thought it was pretty straightforward until I found this:
http://www.interpoker.com/promotions...r_bonus.shtml#
Looks like this site has minimum deposit requirements as well as number of raked hands played (or points gained in this case) however I'm not sure where the books come in, although surely they'd only notify 2+2 when the requirements have been met?
I think I'll change to Partypoker - they don't have hidden T&Cs, I prefer their software and afaik you don't have a deadline of when you have to get your required hands/points, unlike interpoker.