On the one hand, I found it very readable and each character was quickly formed for the reader, making it easy to follow. The pace is also very swift and the blend of the 'real' world and the fairy world is artfully dealt with by Colfer.
However, I also had some problems with it.
The main issue that I had was with Artemis himself. Generally with a protagonist, the reader is supposed to like and sympathise with them and want them to succeed with whatever their quest is. With Artemis, this isn't the case as he is so self-centred, calculating and cold. Colfer has obviously tried to make him sympathetic with the fact that his mother is clearly mentally ill but this has failed because of the way that Artemis deals with her.
The other problem that I had was the constant repetition in parts of the text - particularly in the scenes between Foaly and Root and their 'banter'.
However, despite these problems, I still enjoyed this novel and read it very quickly. I'm just not sure that I would read any of the others...