at the request of Twllbach here's a thread on the books.
I've read the first two and really enjoyed them. I can't get hold of a copy of the third ooh till it's republished at the end of the month. I have it on order and am counting down the days. It's a bit odd as I could get the later books but have resisted the temptation as I want to read them in order.
I know they're young adult books but I really enjoyed them.