Astro Boy is a historically important manga/anime, if only because its success helped in no small part to establish the Japanese animation industry and helped familiarize Western audiences with Japanese media (although it would still be a few decades until it got really popular).

While this is by no means an outright terrible series, its not that good either. Keep in mind that most of the series was drawn with small boys in mind as its intended audience and it shows very clearly. Not to mention that it was released almost 70 years ago, meaning that various parts of the manga have not aged very well.

The art is pretty good but the stories are very simple. While they do often address serious issues like intolerance and violence, the stories they feature in are very simple with predictable resolutions and very little depth. Most of the stories are episodic, which means that the quality of the manga changes with every chapter (although some of them are actually good) and continuity isn't something that's regarded seriously. The characters are flat and boring, if not completely unlikable. The supporting characters have little to no development from their initial introduction and the villains are mostly just there to serve as punching bags.
Astro Boy himself is fine but there's nothing really remarkable about him.

Unfortunately, its historical significance is the only reason I would recommend anyone to read this.