I bought the BB1 book on eBay recently for £0.50. Bargain or what!
I haven't had a chance to look through the BB1 book much yet but the interviews with the housemates after eviction, and background information is what makes the BB2 book worth reading.
I actually found the descriptions of the events in the house to be a bit blandly written, and didn't capture the humour of the series very well (not that I could write any better, mind you!)