You can dislike Sinister, that is a valid opinion to have.
Saying it is all jumpscares is objectively untrue though.
spoiler
It builds tension, then releases it at opportune moments. The snuff films where you know it's coming, the slow realisation that the kids aren't the victims but the culprits, the reveal that the whole time he's just played into the trap, watching the daughter willingly go into the arms of a demon, none of these are a surprise, but they are scary.