Wow was Orion a pain in the butt! He was annoying but at the same time I quite enjoyed the new layer it brought to the story. And I thought Artemis might go crazy sooner or later. 
 As always, Colfer's writing was witty, entertaining and funny. After reading almost the whole series (one to go!) in less than a month, I'm going to feel a bit sad to say goodbye to the characters I quickly fell in love with in the next book. I feel like I haven't had long enough with them!