My full-grown adult husband was scared quite a lot in there!
My son wouldn't even walk near it. Two of his friends watch the show (one older one younger than him) and they would probably go just to be brave, but I bet the younger especially would actually be quite frightened.
While we waited for DH we watched grown adult after grown adult come out looking rather terrified. Some laughing, some not, but very few with "pure" laughs if that makes any sense.
One of the scare-actors when DH went through pretended to be a tourist; he's the one that scared DH the most when the scare finally came.