This book contains two novels from the Chronicles of Chrestomanci series. I have only read the two so far, and they seem to be able to be read independently, occuring in the same world(s) but not needing to be read serially. The Chrestomanci is the most powerful enchanter alive at a given time and features in one way or another in each story.
Charmed Life--Deals with a little boy living in the shadow of his witch sister, finding out there is more about him than he ever thought. I think this book is targeted for young adults, but advanced independent readers through adults could probably enjoy it.
The Lives of Christopher Chant--This actually occurs before the events in Charmed Life and concerns the childhood of a character from the first novel and explains how his life became the way it was when we first met him. While these books in the same world, they can be read independently. There is a lot of magic and travelling between worlds and good versus evil.
I liked Jones' Howl's Moving Castle better, but these were fun, too.