I've never bothered with it so I've decided to watch the first film and I don't get the attraction.

The protagonist is a celeb at school, everyone loves him and he keeps getting shit bought for him and waltzing into the school throwball team.
The guy on the other team gets booed for what seemed to be a perfectly valid play, knocking the Griffo captain off his broom with a fairly well struck shot.

That girl sets fire to a teacher, on a wooden structure, full of other people. She seems like a massive wanker,

The only decent one out of the three seems to be Ron and that's only because he's fucking shit at everything.

At the moment, Harry has broken into the library, smashed a lantern (presumably school property) and is using a cloaking device to hide from a caretaker, who is going to have to clean up that mess in the middle of the night.