There are way too many 10/10 reviews for Slam Dunk so writing a review with actual criticism felt like an obligation.

Characters (0/10):

-Sakuragi: He is your typical dumb yet overpowered protagonist who relies on convenient scenarios and his plot armor. The entirety of his character consists of a tall teenager boy who falls in love with every single girl he comes across, bullies everyone for comedy's sake and is really stubborn. So basically, he digs his heels in making up with some girl who likes basketball and then joins the basketball team just to flirt with her even though he knows nothing about basketball. Of course, once he's already in, he plays the role of the prodigy who doesn't even know how make the ball bounce yet somehow manages to win a match against the captain of the team thanks to Inoue's asspulls. In addition, he also demands first class privileges inside the team such as being a starter, which makes no sense, since he is a beginner.
Ah, and he also harbors a really toxic envy towards Rurakawa just because he is the crush of the girl he likes (and because he is a better player than him).
I wonder what was Inoue thinking when he decided that Sakuragi's awful personality would be perfect to drag the story forwards- because, yeah, all the story consists of Sakuragi creating problems from nothing due to his unrelenting stupidity and the typical tournament-like structure that serves well as a lazy way of pushing the plot onwards.

-The gorilla whose name I don't remember (I think it was Akagi but I don't care enough to look it up): As expected from the cast of a show whose characters rely on lazy clichés, there is, too, a character who is, in a few words, your typical stubborn captain of the basketball team who is an airhead and goes insane whenever. it comes to basketball. That's it. That's the entirety of this character.
Wait, almost forgot, and he is the brother of the girl the protagonist felt in love with (you can imagine that cliché scene in which Sakuragi is trash talking about the gorilla in front of the girl he likes and then he finds out the person he's talking about, the girl's onii chan, is behind his back. You know, peak comedy).

-Rukawa: Even though he is the least ticking off character BY FAR, which is probably because he barely opens his mouth, we can't ignore the fact that he is just another simple character who is another rip off of the cliché character who is handsome, cool and overpowered and is liked by every girl in existence.

-The girl Sakuragi likes: Let us be honest, who cares about her? She is just an element used by our top tier writer, Inoue, to drag the plot forwards by making Sakuragi make contact with basketball.



Art (7/10):

Maybe I am being too generous with this score, but I've got to admit the anatomy of the bodies in some panels are really difficult to draw. The art is definitely the best thing about Slam Dunk, although it's a pity only a 10% of its panels are decent, as the panels are really inconsistent.



Story (0/10):

Disclaimer: I am judging the story regarding the 40 chapters I've read. I dont know, maybe by the 200th chapter Rukawa starts a gay relationship with Sakuragi and dies in a car accident right after breaking up with Sakuragi, which leads to a great drama I couldn't possibly know about, so don't mess around saying the latter part of the story is not about that and blah blah blah.

The story consists of Sakuragi training basketball and showing off that he is a prodigy in every sport ever whereas he repeats over and over the same interactions with his schoolmates- interactions which could be summarised in: sexually harrassing the girl he likes and being a show off with everyone he comes across. In addition, the "comedy" of this manga is based on the fact that the main character is a sexualy depraved bastard, a tyrant and a bully- but hey, it's comedy instead of drama because Sakuragi feigns ignorance after physically assaulting poor guys and because Inoue draws an innocent moe-blush panel afterwards. Inoue tries too hard to make comedy out of physical abuse.
Regarding the matches, they're just as bad (at least the ones I've seen are). Lazy, vague, strategies with no detail at all, typical match structures in which the main characters start losing and then they make a comeback thanks to the plot armor and Sakuragi messing around bothering everyone and acting like a moron 24/7.
Without any doubt, the Greed Island arc from Hunter x Hunter has much more interesting and original matches than Slam Dunk, even though it's not even about sports.



Conclusion:

I believe Slam Dunk is a manga that many elitist wannabes use to let their true, simple minded, self take over their shitty taste while avoiding getting called a moron with no taste, which is what they really are. Maybe I'm resting too much on my personal experience, but there's a bunch of people I know who are huge fans of Berserk, Monster and whatever elitist stuff while they also love Slam Dunk. Leaving personal preferences aside, if we compare either Berserk or Monster with Slam Dunk, we'll see that the both of them are much more (much, much more) complex and original than Slam Dunk.
Well, leaving this latter personal reflection aside, I wholeheartedly recommend you to stay away from this piece of garbage. It's the worst work of fiction I've ever read.