I know that comparing an adaptation to the source book is too close to not looking at the film for its own merits. I won't go into a line by line list of the changes, but the changes bring nothing to the film. They only take away. The changes seem designed to make the movie more like a typical animated film, which the story wouldn't have been had it stuck closer to the themes of the book.
The three characters who really have a story in the book are Roscuro, Miggery Sow, and of course, Despereaux. In the movie, only Despereaux is painted with any real background and character, and all of that is noticeably different from the character in the book. The subtleties that made him so charming are gone, replaced by a devil-may-care nature. Where the Despereaux in the book found heroism in himself, where he didn't expect it, the Despereaux in the film was depicted as being born for heroism. This difference sums up the change in theme and direction of the movie. It becomes much more typical because of this change, without room for character growth. Roscuro and Miggery Sow are similarly rewritten so that they don't develop. The plot is rewritten around them, with strange additions such as the chef and the man made of food.
At first, I was confused by comparisons to Ratatouille, but after seeing the first twenty minutes of this movie, I understood it, and perhaps they have something in that comparison. I can't think of a good reason for some of the additions that came out of the blue into the movie adaptation.
The three characters who really have a story in the book are Roscuro, Miggery Sow, and of course, Despereaux. In the movie, only Despereaux is painted with any real background and character, and all of that is noticeably different from the character in the book. The subtleties that made him so charming are gone, replaced by a devil-may-care nature. Where the Despereaux in the book found heroism in himself, where he didn't expect it, the Despereaux in the film was depicted as being born for heroism. This difference sums up the change in theme and direction of the movie. It becomes much more typical because of this change, without room for character growth. Roscuro and Miggery Sow are similarly rewritten so that they don't develop. The plot is rewritten around them, with strange additions such as the chef and the man made of food.
At first, I was confused by comparisons to Ratatouille, but after seeing the first twenty minutes of this movie, I understood it, and perhaps they have something in that comparison. I can't think of a good reason for some of the additions that came out of the blue into the movie adaptation.