I think this is the first time I have ever said this, but I like the movie a lot more than the book. I am not saying this because I saw the movie first, but because the plot of the movie is just so much more rich, and indeed magical, than the book.
I saw the movie for the first time many years ago before I ever found out that it was inspired by the book, which I actually only found out recently. I say that the movie was inspired by the book because the plot differs in a lot of ways even though we see all the main characters from the novel. On top of that, you see a lot more magic being performed in the movie than you ever see in the book. In the book, it seems as though only the aunts, who are incredibly elderly, can perform spells and magic, Sally and Gillian never seem to do any. Gillian, Sally, and her daughters just seem to be sensitive to the world around them, they seem to be able to perceive things that most people can’t or otherwise just choose to ignore. The fact that there is very little magic being performed makes the book just ok, in my opinion. The book is more about the bond there is in being related to someone by blood. It gives a very girl-power quality to the story, which I think is ultimately what the author was going for.
I am much more interested in reading the prequel to this story, The Rules of Magic, in which we follow the aunts Franny and Jet, along with their brother, when they are young. Maybe in it we will get to see how they learned to do magic, which is what I was hoping for in this book. If that disappoints, there are an additional two books in the series.