I loved this book from beginning to end. It's Diana Wynne Jones so you know it's good, but this one was like listening to a light, funny song that made you want to sing along.

In a nutshell, the magical city state of Caprona has two major magic families. Unfortunately they've been feuding so long they can't meet in the street without the sky raining cowpats. When an evil enchanter starts a war, can some younger members of the two families trust each other enough to save the city.

As usual the magic is creative, the characters are likeable, interesting kids who don't always see themselves as clearly as others do, and DWJ seems to have a lot of fun writing big Italian families. They also have awesome cats.