When I first saw the trailer for Mr. Magorium’s Wonder Emporium I got the distinct impression that the marketing department was mostly targeting kids. The poster gives me the same impression. It’s colorful, it’s bright, it has a bunch of stuff flying around and it has Dustin Hoffman with a very silly grin. What it doesn’t have is many elements that are likely to appeal to those of us who aren’t children anymore. Sure, Natalie Portman in any shape or form is bound to attract some of us, but that is pretty much it.
I don’t personally like the poster very much, but that doesn’t mean it won’t be effective with the target audience. And plenty of films with close to none adult appeal managed to do just fine in the box office by convincing the kids to drag their parents to the movies.