much of the main plot points of the film were faithful to the books, that said yes, several characters were either changed, or outright omitted, part of the reason people were tolerant of this, is because enough of the main plot was left intact, it was a star studded affair for a series and genre that had been left to rot by hollywood for decades, so it had a huge spotlight shining on it to be a success, which meant they had very very small amounts of wiggle room when it came to altering things to make sense with the screenplay.