My tween-age daughter has become a fan of all things vampire thanks to the "Twilight" books and films, so she asked me to take her to see this movie, even though it's based on a different series.
Although "Cirque du Freak" shows its "young adult" target audience, it was not as bad as many teen-oriented films I have seen. It had an interesting, if simplistic, storyline, and was effectively filmed. I agree with the comments that especially commend the Freak Show scene as an early high point, but the rest of the story moved along at about the right pace, and I never found myself bored.
I'm told the teen lead was very attractive, but he's not much of an actor. His evil counterpart, played by Josh Hutcherson of "RV," was somewhat better. I'm not a real John Reilly fan, but he did a good job in his leading role. Willem Dafoe was wasted playing, essentially, a vampire version of John Waters. I would hope that Ken Watanabe and Salma Hayek would have a bit more to do in future installments. Ditto Orlando Jones, who hasn't done much since the horrible "Evolution" nearly killed his career. I also hope the character of Mr. Tiny is written better in the future; this guy was a pain to watch, and came off more like a sweaty pedophile than a supernatural referee or whatever the hell he was supposed to be.
Parents: nothing to worry about here. I'm not even sure how it came in at PG-13, unless there was some mild profanity sprinkled in that I don't remember. This might be a little complicated for little ones, but ages 8 and over shouldn't be scared by anything they see here. Best of all, it's not too painful for adults to watch if you must. Then again, I'm a veteran of the Pokemon movies; I've been to movie hell, so I can sit through anything now.