It really has been a while for a horror movie to make me jump. And to be honest the first fifteen minutes did make me wonder if this movie was going to be any good. And yes,it did. In this case the slow build up does benefit the tension. And for once they actually put in characters you like. Not that you learn to know them well. But at least we do care for them which of course is crucial in movies like this.When events start happening it is asked of you to put aside logic which you will be rewarded for. So while Insidious is filled with creepy and scary moments it is not always super scary. But after a while it does get very thrilling and tense and it doesn't let go. To tell more would be a crime. The less I tell the better the experience. A must watch movie!