Adam Goron’s review published on Letterboxd :
Insidious begins with a lot of promise - it's full of quiet moments of slo-burn suspense, and gets great mileage out of its implications. But the final half of the film devolves into something so wholly ridiculous that it absolutely demolishes all the progress that had come before it, and turns in to a kind of wannabe Raimi farce with a dreadfully mismatched tone. Yuck. Talk about wasted potential.