I've read all the books - there are 9 with number 10 coming out this year (I think). The books vary from the TV series, and I think the books are better. They are like the TV series in that the sex scenes are a little on the graphic side but its a pretty good series.

Buy or borrow one and see how you find it. I got my from amazon and I got the box set of 8 books for teh same price I would have paid for 3 in the bookstores.