They're young adult books now. Keep that in mind Croes. Nevertheless they're not written like young adult books and since I read Harry Potter I've discovered I like a lot of young adult books better than adult ones. (I liked a Song of Ice and Fire for instance, and Martin is a very good writer, but I liked the subject matter of the Last Apprentice better.)
And the Last Apprentice actually surprised me as to who Tom Ward's real mother was. It's very hard to surprise me, especially in literature, but I would have never know who his mother really was til I actually got there in the story. That alone was very impressive to me. By the way, don't read about who his mom is on the internet. It will spoil the surprise. And it probably will surprise ya.
As far as I know, in the States at least, the first book is The Spook's Apprentice. In Great Britain they're called the Wardstone Chronicles. He's also written a couple of stand alone books that tie in and actually tell stories of before Tom ward became a Spook. Those books are good too but I'd pout them off til later so as not to spoil anything. Try em, I think you'll really like em. The concept is very original I think, and best of all, I like the fact that Tom and the Spook work alone. I like books where the main character works alone or with only one partner or so in very, very dangerous situations, with no chance of rescue or extraction. That really appeals to me.
I just finished one of the stand alone books, and now I'm reading Rise of the Huntress. Got it today. Looking forwards to it. Anyway your local library will probably carry the series in the young adult section.
There's talk of a film too. I hope so. If they do it right it should be spooky as hell. Literally.