I 100% know and understand why we hate Rowling, she deserves all the hate she gets, but why do we hate the work itself? I watched those movies when I was little when they were on TV, now couldn't care less, and only interesting part to me are mythical creatures/monsters. But I still forgot why do we hate it so much??
There's a lot of it, as you can see in the other comments.
I personally just hate her writing, especially her ludicrous naming sense. This thrown me so much off that i stopped reading at half of book one. For context, i can read even the dumbest books, but retched at this one - it was THIS bad.