This is a childhood favourite for me and as I got older I've came to appreciate the master piece this film is. It deserves way more better ratings and its shocking how poorly received it wad by critics. Some spoilers ahead though!
The film tackles serious subject matters such as can artificial life feel emotions or are they simply programmed to be that way? Astro boy explores this theme displaying that robots are more than capable at feeling emotions at their own will , Astro in the film presents this within the film, despite all the turmoil he faces and the utter devastation he is exposed to after his father tosses him away due to him causing more pain for him , he still remains a incredibly good being. Other themes looked at include the life , death , the good vs evil nature of humans contrasting with artificial lifes , megalomania and the risks of technology. The film actually presents real human emotions such as crying which is usually poorly produced within animated films.
Overall, this is an absolutely fantastic film. Honestly, just watch it you won't regret it.