You never know! My girlfriend thought she would hate it, her and her family and friends and everything she wouldn't last fifteen minutes... she ended up buying a Frequent Fear pass. She's a huge fan now. Gets a kick out of the houses, LOVES making friends with all of the scareactors in the scare zones, loved the shows, everything.
HHN is a totally different thing than a horror film. Films for the most part take their time to build suspense, manipulating you over the course of an hour or two. As opposed to the slow burn of a movie, HHN is trying to get you within a span of minutes, repeatedly many times over several hours. It's a completely different dynamic, and some people can handle that dynamic easily who might not do great with horror films (and vice versa). Most of the houses and scare zones are trying to get you with misdirection, have a cool effect or set piece or something in one direction, then something jumping out at you from the other direction, so it can almost become like a game of trying to figure out what their tricks are.