Stupidest/worst changes from book to movie
Obviously stuff needs to be cut in the interest of time or pacing but this is about changes that renders thing incoherent rather than for the sake of time.
Changing Harry and Ron sneaking out at midnight to duel Malfoy and Hermione following them to keep them out of trouble and their subsequent stumbling upon Fluffy and Hermione reprimanding them...to the 3 accidentally getting on the wrong staircase and stumbling on Fluffy....and Hermione reprimanding them. Stupid because Hermiome acting like it was Harry and Ron's fault now makes
no *beep* sense in the movie (Philosopher Stone)
Angry Dumbledore for no reason (Goblet of Fire)
The Durmstang entrance. Doesn't ruin anything it's just so retarded.
Cho selling out the DA but then being revealed to be forced to do so by way of veritaserum. Changing it so Cho sells them out was fine as the movie didn't have the time to devote to her emotional problems and jealousy issues. But revealing she was forced to do so and leaving it at makes Harry look like a dick for not apologizing. Seriously what was the point of saying she was forced?
Hacking Snape's backstory to bits
Casting a young actor to play Lily that doesn't have the same eyes as Radcliffe.