The title says it all

Rating: 7/10 (3 April 2011)

"Insidious," has been one of the few well-made horror films that have come out in the past several years, that kind of stays with you and gets under your skin. While other reviews have noted the obvious parallels to other horror movies - Poltergeist, Paranormal Activity, etc. - it adds a rather original take on the whole genre of haunting and possession. While I liked the movie overall, I couldn't help, but feel it suffered from an issue that seems to be a common pitfall for most horror films.
I'm often surprised how nonsensical the main characters act in horror movies which make me not sympathize with them. For instance, why would Renai be fine with just hanging out at home by herself, after all the craziness of the one night, where the front door is opened, and she sees that man by her baby's crib? Josh seems to be unfazed by the bloody hand/claw print Renai finds on Dalton's bedsheets. Yeah, just normal bloody claw prints on the bedsheets, see them all the time. And after Dalton's room gets destroyed by no apparent thing, he still says to the paranormal investigators, "You guys are just taking advantage of a bad situation"? Really? But what really got me was how Josh's mother, Lorraine, kind of just only appears when they move into their second house. With all that's happened to her grandson going into a coma, you would think she'd make an appearance at some point during the first part of the movie and impart her knowledge to Renai then. I mean was she traveling in Bali the whole time? Where was she until this point? It just felt so arbitrary that you really felt she was more of a place device than a character.
Still, I appreciated the fact, that the scary moments weren't the obvious "let something jump out when the music builds up" that you get with most other movies. Interestingly, the scariest moments were never really things having to do with the demon, but the little things. Like the child facing the wall in the laundry room, while Renai is walking through the house, and she doesn't see him there. But I really liked how the movie gave us little clues as to how Josh, was not or rather more than just Josh, and it's only until the end, that we realize Elise's efforts to rid Josh of the hag had failed, and he had been possessed this whole time. And it's that "Oh sh*t moment," that's what makes it so creepy in the end, because his seeming normalcy in the face of it all undermines those other movies of what possession would look like. Instead, it's something that's stealthy, and creeping. It's insidious.