Mediocre anime film that has an unoriginal plot but plenty of visual treats. It is superior to some of the sappy crap Disney has been releasing over the past 25 years, but it is inferior to the stuff Studio Ghibli is making.
Steamboy is a great anime classic. This is as good as Spirited Away and Metropolis. The only issue is violence, but there's only a little bit of blood, about two seconds. But the violence is still there, so kids under 10 shouldn't watch Steamboy. I think 11 and up is great.
Besides a minuscule glimpse of blood in one scene, the violence is limited by what would normally be seen in cartoons, even if higher violence is suggested, it isn't shown.
Steamboy is by no means inappropriate for children, but it is still a miss as it generally lacks any sort of decent plot, story or message whatsoever. The only thing it has going for it is overpriced visuals.