For the first part of the JoJo Series, Phantom Blood, while not as good as itself, it's very good as a starting point. The way we see Jonathan going from a innocent and naive, but still courageous and honored kid, to a full-grown adult, ready to sacrifice himself for the well-being of others, is very well-done.

While the art itself isn't that good, seeing how it evolved until the current Part 8's style (specially if compared to the same characters in the new style, shown in the artwork for the "JoJonium" covers), show how much Araki took his time to improve itself (the same with the story).

A good manga if you like a good story, and a even better gateway into one of the biggest manga series ever made.