I've been a big fan of all 4 movies, the way they tie the current movie to past movies, explain stuff from other movies with new content in the sequels, etc. It's all super well thought out, plus great scares and visuals.
This movie had absolutely none of that. The story seemed cobbled together, the climactic final part has a ton of unanswered questions (Not good ones, more 'how does that even make sense?'). Good scares, that's what saves it from 1 star. Some very original and surprising stuff there, but otherwise this doesn't stack up to 1-4 for me.