Astro Boy's pilot was basically a Pinocchio/Little Orphan Annie kind of story. First of all, this is at a time where humans and robots co-exist. It starts out when a professor at the Ministry of Science has a son who dies in a car accident, so he builds a robot counterpart of him, naming him Astro Boy. However, the dad didn't like how Astro couldn't express human emotion, so he gave it away to a circus performer. Eventually, he is "adopted" by another professor named Ochanomizu and becomes his legal guardian. The rest is sort of like a Batman kind of show. Just Astro beating the crap out of criminals. =P However, there are some clever and remarkable episodes, like the time Astro is in space and he must choose between his new lover or a crew of 100 men stationed there for alien research. It's all clever. =P
Astro Boy was considered the start of anime altogether. It was WICKED popular around the world.