Diamond Is Unbreakable's story begins with a few missteps, that of focusing on an illegitimate son thus almost rendering Joseph Joestar's courageous mission in the previous volume moot and making him look like a jerk (although this is played for laughs), and also more importantly slightly retconning the evil granny character of Enya by having her be a source of more trouble for the worlds citizens by going around with a mystical bow and arrow and randomly shooting people, giving them randomly assigned 'stand' powers.
Author Hirohiko Araki goes full on with crazy stand powers this time, emboldened with what he achieved in part 3 and the introduction of the crazy powers and their potential, you'll see a full range of quirky abilities that cause as many laughs as they do terror.
The main character of Josuke is thankfully livelier than the stoic and bland Jotaro of part 3, and with a more funky wardrobe courtesy of Araki's brilliant fashion sense. In fact the stylistic choices throughout the saga continue to get more and more inspired in their lunacy, it really is a joy to read and appreciate the unique art on display.
Josuke is surrounded by a motley crew of friends, family, enemies, enemies turned friends, friends turned enemies, random ghosts, aliens, and animals with attitude. They all fit one genre trope or another, but they're all very entertaining and very distinct.
Part 4 has awesome battles and abilities as usual for the franchise, and is almost worth it just for an action scene towards the latter half involving a motorcycle, a baby carriage and an unstoppable 'stand'. Araki's battles rarely ever rely on what today's staple shonen bestsellers always use: the old 'allies appear from nowhere and save the day' routine. Araki's characters get pushed and pushed into tight corners and work their way out using brain power, or if their allies do appear, it’s because of planned out teamwork, not mere coincidence or luck.
And even though there are a lot of 'standalone' stories in part 4 as opposed to a big mission, they're for the most part well thought-out and have plenty of great payoffs. They all thankfully advance the plot or character relations in some manner too, which is essential for good storytelling using a standalone format.
Especially the last story arc of Part 4 which is excellent indeed, with our plucky good guys facing-off against the saga's best villain. Yes better than Dio and his generic world-domination plans, Part 4's villain's threat is much more terrifying for its relation to reality. It’s easier to be threatened by a sociopath who avoids fights and attention (knowing full well he can silence anyone he pleases easily) and preys on the weak for his own satisfaction.
Despite its flaws and rocky beginning, part 4 sustains JoJo's tendency for making readers laugh out loud at the surreal humour and quickly turn pages in anticipation of the next outstanding battle and all the twists and turns it entails. Even Joseph's playa ways, which I cited as an unnecessary misstep, gets a humorous payoff at the end.
I can barely think of anything negative to say about this manga after all. JoJo's Bizarre Adventure is probably the greatest shonen ever, its amazingly long publishing run and popularity proves it.
