As the starting point for one of the longest running manga series', JoJo's Bizarre Adventure Part 1: Phantom Blood, while certainly not very flashy, provides a solid foundation on which Araki builds the rest of the JoJo saga.
The story of Phantom Blood is simple: save the world by killing the false childhood friend turned vampire. To accomplish this feat, Araki introduces "Hamon", a fighting technique based on breathing. Though an interesting concept, Hamon is not the most creative feature to be found even in shonen manga, especially compared with the wonderfully imaginative "Stands" introduced by the third JoJo series "Stardust Crusaders". Nevertheless, along with the powerful fighting technique comes equally powerful foes derived from English history with the intention of putting an end to Jonathan Joestar's quest for revenge. This of courses makes for plenty of exciting action, but at the end of it all, the story is still highly generic. An emotional ending wraps up the five-volume series quite well, but it is only enough to carry quality of the overall story to a mere "fair" level -- not bad, but nothing to be amazed about.
Like the story, the characters of Phantom blood are also very simple. They are mostly distinctively black-and-white. The good guys are exceedingly noble and just, while the bad guys are overwhelmingly sinister and cruel. There are a lot of exaggerated emotions to be seen from the characters -- tears would be shed at the hero's act of benevolence, while the vile deeds of the villains would always be accompanied by exclamations of sheer horror. But because of how excessive it is, the reader would often passionately cheer for the heroes and boo for the bad guys, adding satisfaction to each of the heroes' victories. The simplistic characters of JoJo, while not outstanding, carry a hint a undeniable charm.
The art style of JoJo is definitely its selling point, though it may not appeal to everyone. The physical build of the characters is Phantom Blood's most obvious distinction: virtually every male character who makes an appearance dons the physique that would be the envy of bodybuilders. Araki loves to draw muscles, and a LOT of them, to point where he would draw muscles that do not exist in actual human anatomy. As a result, the men become hulking giants with clothes so tight that it makes make one wonder how they can manage to breath. However, the burly heroes and villains look great while fighting, and combined with Araki's bold style, the action is both gruesome and vivid. The tone of the panels are dark due to the heavy use of shading, which serves to build the dark atmosphere of most of Phantom Blood's settings. The details on the monsters make them so hideous that instances of their often brutal demise are greatly satisfying.
If you are looking for a simple beat-them-up shonen manga and do not mind the lack of creativity in the story and characters, JoJo's Bizarre Adventure Part 1: Phantom Blood is worth a look. It is not the best the JoJo saga has to offer, but its unique and dynamic art, accessible characters, and even the simple but generic plot still offer up plenty of thrills.