Manga Unexpectedly Good For A Detractor Of The Franchise
Apart from Part 7 and 4, I hate JoJo. While my expectations couldn't get any lower after Part 3, Part 4 is more than enough to warrant a positive response for me.
Don't get me wrong it's not perfect, but to me, this is what JoJo should be. Part 4 focuses on mundane situations for the most part. It reminds of a video game where the side quests are as interesting as the main story. I loved that each episode wasn't just another life or death battle against some Stupid Evil villain, but a more unique formats like earning cash. Some even had An Aesop. Overall, it creates a bizarre but enjoyable experience.
The Rated M for Manly nature is downplayed to where it's not nauseating. As a result, the characters feel more like people, rather than Testosterone Poisoning. Josuke, despite being even more generic than the previous protagonists, is a much better lead. His status as an Audience Surrogate, and useful stand makes him a likable Escapist Character. But his motive, while believable, is uninspiring. Koichi's someone you wouldn't expect in a series like this and is a welcome addition. Okuyasu's actually funny compared to the previous "JoBros." Bringing back Jotaro means they can focus on other characters more. Of the supporting cast, Shigechi, Yukako, and Shinobu stand out.
The animation and music is on point for the most part, although besides a few tracks, there's not really anything memorable. The pacing is also a bit off, like going off topic in the 2nd half. It feels like a game where you can't progress to the next main mission until you complete a bunch of irrelevant side quests.
As for the villain, Kira is a vast improvement over Dio. Now, while I love Kira as a villain, there's a big problem with him: I end up Rooting for the Empire and downplaying his evil traits when I know I shouldn't. It's tough to dislike him because we see very few of his murders and the ones we do see are either against Asshole Victims, or the victim was too underdeveloped to make me care. He also grabs the Idiot Ball once or twice. Overall, some of the best episodes revolve around Kira and he deserved even more focus than he got.
The other flaw is that there's no true Sacrificial Lion, which undermined Kira as a threat at times. Perhaps him killing someone I truly cared for would've made me Love to Hate him.
Best thing is you don't need to watch the previous parts and waste your time to watch it like I did. So take it from someone who loathes the JoJo franchise that Part 4 is worth a shot.
Manga Mixed Feelings
I've heard that Diamond Is Unbreakable, the fourth Part of Jojos Bizarre Adventure is an Even Better Sequel to Part 3, but I don't fully agree. It does some things better than Part 3, but has enough flaws that I enjoyed Part 4 less overall than Part 3.
The main plot of this Part involves Jotaro, The Hero of the previous Part, traveling to the town of Morioh to meet his grandfather's illegitimate son Josuke, as well as to track down a Serial Killer hiding in the town. This Part has more of an emphasis on story and Character Development than Part 3, but unfortunately, worse pacing. The first half is rather slow, and while things get more interesting after the Big Bad debuts, it reverts to the Villain of the Week format when the villain goes into hiding, and doesn't really pick up again until the climax.
Part 4 has more Character Development than Part 3, which is a good thing. While Josuke, the protagonist, is merely decent as a Jojo, Part 4 has one of the most interesting main villains in the series. Unfortunately, the secondary characters aren't always used well, with many only becoming relevant for an episode or two after their arcs at best(although since some are rather unlikeable, this isn't always a bad thing). Seemingly important characters like Josuke's mom and grandpa are quickly forgotten about, and some minor plot threads never receive adequate resolution.
One plot element I especially disliked was Josuke being Joseph's illegitimate son. It's not like Joseph to have an affair, and worse, this plot element is barely elaborated upon, save for one episode of awkward interactions between Josuke and Joseph. We never learn why Joseph cheated on Suzi Q, nor do we get much closure for Joseph's relationships with Josuke and his mother. As such, it seems like an excuse to have Josuke be of the Joestar bloodline.
I have mixed feelings about the more exotic Stands in this Part. On the one hand, many of them are more interesting than before; Josuke's ability to "fix" anything is one of the more interesting protagonist powers I've seen, and the same goes for the Big Bad's Stand. On the other hand, it's harder to write good battles for some of the more complex Stands, and some, like Koichi's, come off as a case of New Powers as the Plot Demands.
As a minor note, while I overall liked the soundtrack, especially the Big Bad's theme, I found the opening and ending credit songs somewhat disappointing compared to those of the previous Parts.
If you can get past its flaws and stick around through the relatively slow first half, Part 4 is a mostly worthwhile experience.