Let's talk about MCs first. The story revolves around the rivalary of Jonathan "JoJo" Joestar and Dio Brando, they are presented as very black and white i.e. Jojo, the protagonist along with his father George Joestar, are incredibly good, brave, righteous, strong and kind-hearted gentlemen, while Dio Brando (and his father) are selfish and pitiful drunkard pigs, filled with hatred and evil. Dio hates JoJo, for just no reason, while JoJo presents a hand for friendship, always ready to Trust Dio, just to get betrayed again.
There is no depth in these characters, and the reason of them to be good/bad is due to their respective bloodline, and since Phantom Blood focuses a lot on character development (since first 2 out of 5 volumes are just an insight on the characters) this issue becomes painfully bad, unbearable.
In the beginning I felt that they will show how Dio became as is because of how he was treated what his father did to his mother, and would be given a chance for redemption, but after speed wagons claim that he was Evil from his childhood, it became very clear that there is no such thing in this Manga, Dio is bad for the sake of being bad, and that is very weak characterization.
Coming on artwork, it is quite good, from the standards of 80s, as everything was hand drawn back then. However the proportions do make your head twirl at times. How can a 12 y/o have such muscular and gigantic body, even for Manga based on masculinity and muscle strength, it's too much.
Finally, It is the weakest work in all of Jojo series. A super boring and completely passable one. I'd rather just read Fist of the North Star. The only reason I would ever read this is because it sets the base for later arcs for the series.
One should be passing this arc entirely, rather check out the anime of it, much more interesting and a better way to experience this.
