I really enjoyed Liar by Justine Larbalestier, and for that reason I decided to read her earlier books. And now I'm kind of wishing I hadn't, because I didn't like them nearly as much as I did Liar.
First of all, the world-building in How To Ditch Your Fairy was excellent. It wasn't described to excess, but rather, you're thrown into the world of New Avalon, and you figure out how it works as you go. The characters also used slang (thankfully, a dictionary of the terms they used could be found in the back). New Avalon was built very thoroughly.
The premise of a place where most people had a personal fairy was also incredibly unique.
The main problem I had with this story was Charlie being so ungrateful with her fairy. A parking fairy is not bad - it's actually incredibly useful. Her main problem with her fairy was how Danders exploited it, but I just couldn't take him and his caveman dialogue seriously. Charlie's father and sister didn't even have fairies, and she spent the entire book trying to upgrade hers.
The ending, even for such a light fantasy, was too happy for my liking. I would have found the conclusion more realistic and appropriate if the last chapter were left off.
Overall, How To Ditch Your Fairy was a light and funny novel, if a little superficial.
I give How To Ditch Your Fairy a 3 out of 5.