I thought it was aight, and I dislike Shyamalan's post-Unbreakable movies so much I don't even talk about any of them.
The thing is, you gotta be aware going in that it's pretty much a comedy that plays with horror tropes (found footage in particular), if you try to watch it as a straight-up horror you're just fukking it up for yourself. There's also a couple of things here I enjoyed such as the small straight forward character arcs of the brother and sister coming to a head in the final act. It could've been handled a bit more subtle because it's practically telegraphing how things come full circle but since the movie was short and straight to the point as a whole I could accept it.
Regarding the twist, I saw it coming very early but I think it doesn't matter that much whether you figure it out or not because the twist isn't the revelation/climax of the story (like it was with The Sixth Sense and Unbreakable), it is instead used to add an additional dynamic (higher stakes, if you will) to the final act, and for what it's worth, the suspense is there when it matters so that's a plus.
I wouldn't consider the movie redemption for Shyamalan, but at least with this project he's embracing a different enough yet still familiar approach that could get him there some day.