The book is good because it describes all the scenes that are important the knowing what is happening during the story. Also it shows the important scenes with great detail and explanation in what happened . It also doesn't stray off topic as much as the movie. The book also has more detail in how Sirius Black got into the castle .
The movie is also good because it shows whats actually happening in the scenes that the book didin't have much detail about. Also in the part where Professor Lupin turns into a werewolf is a bit creepy, which I like. The movie also leaves out a lot of impotant details the are vital to the story.
The differences in the book and the movie are that the movie leaves out a lot of detail that is important to the story. For example the story says that Sirius Black sent Harry a letter saying that he can visit Hogsmeade, but the movie doesn't show that. Also movie also goes off topic a lot. The book describes gruesome scenes with great dialogue, but he movie just shows the scene without detail.
The book is better than the movie because it leaves off a lot of detail in what happens after Harry leaves he aunt's and uncle's house, in what happens inside the Leaky Cauldron when harry gets there, etc. Also the book is better because the book stays on topic and describes the most important scenes.
Rowling J.K., Harry potter and The prisoner of Azkaban, New York, New York, Scholastic Press, 1999. print