Hollywood marketing doesn't seem to understand the concept of a kids' movie that doesn't insult kids' intelligence, and expects them to follow along with a serious story. That's why the advertising for this film made it look like a generic action-comedy. Hollywood assumes that kids aren't interested in character drama and would rather see "I have machine guns... in my butt?" Had I only seen the ads and not read reviews, I wouldn't have bothered with this film.
But early on, we get the death of a child, and his grieving father, a scientist, deciding to create a robot form of his kid, with his son's memories. Eventually, the father tells the robot that he's not really his son, and to leave. Astro Boy, confused and upset that what he was programmed to think of as his own father had kicked him out of the house, does indeed leave and ends up meeting a bunch of orphaned kids in a junkyard.
Many heady themes are touched upon in the movie, ranging from the aforementioned parental abandonment and loss of a child, to prejudice and class warfare. Despite the procession of jokes to lighten the mood, the story itself isn't the happiest out there, but it's generally well told and exciting. I often couldn't tell where the story was going to go next, and yet the many plot twists made sense and worked to make the story more interesting. There were some generic and totally predictable elements in there as well, and the whole "blue energy = good, red energy = more powerful but bad" was corny, but in general, the plot was enjoyable.
It's a royal shame that this movie killed the company that made it. I do wonder if the horrible marketing was at least partly to blame. Hollywood doesn't seem to understand how to deal with anything that breaks their precious formulas, and an intelligent, emotional film about a boy who dies, is more or less rebuilt as a powerful fighting robot, thrown out of his house by his own father, moves in with a bunch of orphans led by an engineer, and ends up having to save people from a giant robot threat, is something that must blow Hollywood marketers' formulaic minds and present a dilemma for them. Their decision to focus only on the "fighting robot" aspect and the dumber comedic elements made a surprisingly enjoyable film look like generic garbage, and could very well have killed the audience.