SBR (Steel Ball Run) takes place in an alternate universe. Denominationally, it was what Jojo's needed after part 6, a brake on the original story, to prevent Araki from getting lost in the play itself.
Story: First point, SBR is not a continuation, it has a story with beginning and end, and that is good. My reason for not giving a 10, is simply the beginning, more precisely the first 20 chapters, and do not misunderstand me, I am not confusing the construction of the story with slow narrative, the point is, the beginning has a slower story and which does not show much after a few chapters, this is only a bad point, because it extends for a few chapters, after that, the story is finally developed, begin the mysteries and progress of the plot.
Definitely, this part should be the most mysterious in all Araki's work. A magnificent point of the work: it covers our whole world, using the real elements to build a narrative, this is magnificent, when you read the manga, you feel like something very realistic.
The story has a perfect progress after a few chapters, is not too fast, nor slow, and a point that is worth noting: it is one of the few parts of Jojo's, without an accelerated or "rushado", something that was only presents in some parts like Battle Tendency and Phatoom Blood (and a little on 4 and 5). The plot is wonderful, the story is complex, it has a wonderful tempo and a magnificent ending.
Art: denifitivamente, the author's high point, absurdly magnificent, I can not find any defect in the art.
Characters: Ah ... here we have a magnificent point, the characters, the series begins putting Gyro Zeppeli as protagonist, something wonderful, and before talking about more, I need to make evident some points: SBR uses some characters from other parts, from (Jonathan, Caesar (not sure) Erina and Dio) these characters, contrary to what you imagine, do not have the same personalities and characteristics as the others, they are surprisingly excellent, Jhonny is perhaps the only Jojo's to have a three-dimensionality, and hanging on to the more inhuman side, Gyro, almost the protagonist, has a remarkable personality, fun and a magnificent story, Lucy, absurdly important to the plot, here she does not get played to the end or something, she actively participates in all the conflict and script, Diego, well, here is complicated, you may prefer Dio Brando, but some points make Diego better: his story, here, much more complex, and conveys something that would motivate someone to be just the way he is. Diego is extremely important to the story.
Lucy: Wonderful character, although young, she is determined and courageous, very different from Erina (Part 1), super important to the story and script.
Some other characters worth mentioning are: Hot Pants; Ringo; Stephen.Personages important to history and its development.
The main villain: Well, I admit that I still prefer Enrico Pucci, but definitely, Funny Valentine is Jojo's best villain up to that point, absurdly magnificent, well-grounded motives, his goals, personality, and even his powers, make him a great antagonist or villain.
Something to highlight: Along with part 5, SBR highlights the background stories of the characters, each story has its touch and realism, making them unique and a point 10 in the work.
Enjoyment and Overall: SBR is one of my most beautiful and well-made stories I've ever seen, it has a spectacular storyline, unique elements, a perfect Araki touch on manga, great art, well-crafted and well-developed characters, a really sensational "villain" , is fun to read, of course, is a sleeve hanging to the seinen side, which makes it a work that requires more attention when reading, incorporates well the sense of adventure.
The only thing that disappointed me, and this does not interfere with the work, was to have read with a giant hyper, so I advise, do not read SBR in the expectation of being the best work in the universe, read with the "feet on the floor", watch out for the details, enjoy each chapter, you will realize that it is a magnificent and well made story.
"This is the best part of Jojo's? Well, I'll say yes, I have not read Jojolion yet, so I will not think about it, but definitely, this is a masterpiece.