I took one for the team and saw this as a matinee for under $6.
I really liked it. Probably one of the least pretentious things he's done, which helps immensely. I'll post more later on laptop.
EDIT: It's not anything with long-term dramatic resonance (like The Sixth Sense or Unbreakable), but it just does what he wanted it to do, it's entertainment. Sometimes it's funny, sometimes it's just kind of unsettling/creepy, and he actually makes some gutsy choices with music and humor that somehow work. And yeah, there's a twist, but you're expecting it -- you want to understand what's going on, and finally it does make sense.
IOW, he basically blew a wad of his own money to prove he can still make an effective movie, on a shoestring budget. So... he accomplished that. He even does generally stick with the found-footage convention consistently (compared to some found-footage flicks that break the convention). He also opens some various threads and backstories that he manages to completely weave together by the end, and fairly organically rather than noticeably forcing them as sometimes he does.
The boy (Ed Oxenbould) is actually rather amusing. Olivia DeJonge as the girl and budding documentary-maker exudes a bit of the dramatic pretension (in beautiful teenager girl style) that Shyamalan is accused of and at times seems to poke fun at himself. Dunnagan and McRobbie do well in the role of the grandparents, and Hahn is a down-to-earth, unsophisticated but accessible and warm mother just doing her best.