Took my little brother (4 years old) through Broom today. And he didn't really like it.
He wasn't a fan of the forced interaction: a stranger trying to encourage him to go forward and interact with stuff just didn't work. He's not shy or anything either; just being a small dark space made him not want to interact. The effects were decent and got a good reaction, but it makes it a passive experience.
So yeah, someone who's bang in the target market for this didn't like it. My personal opinion means little in that sense, but I was even less keen: it's an experience which is too focused on young children, the scenes are very cramped and awkwardly paced and it just doesn't seem like something which the whole family can enjoy.
Particularly a shame given the theming and effects are good.