What made Black work?

[Totamo]

Evil Goku is a terrible idea and should have been as generic as all hell, yet one of the few things many agree with is black was the best part about the arc.

[sintzu]

In the anime it was Nozawa's voice.

In the manga it was him being Vegeta's punching bag.

[Chuquita]

It was because he was so 美しい.
He somehow balanced being both a legitimate threat and being incredibly hammy in his love for himself. Him and Future Zamasu's airtight teamwork in the anime was a force to be reckoned with.

[Ki Breaker]

What made him work was the fact he wasn't an evil goku, evil goku is still an odd idea

[TheMathemagician]

What made him work was the fact he wasn't an evil goku, evil goku is still an odd idea

This. Him not being an evil Goku was great. There's also the fact that he was somewhat flamboyant and has a weird obsession with Goku too. Nozawa certainly helped with it. Wasn't much to like about Manga Black though unfortunately.

[Cipher]

What made him work was the fact he wasn't an evil goku, evil goku is still an odd idea

Going to second this. What made him such a fun, hammy villain was the fact that they didn't try to incorporate elements of Goku's character into a twisted or evil version of our protagonist. Instead, we got an enjoyable mustache-twirler, and a fairly interesting villainous arc for Zamasu (and I don't mean in terms of any meaningful philosophy or nuanced characterization, but in his willingness to throw his old life away and possess Goku in order to achieve his goals).

Evil Goku, in terms of putting a dark spin on his character motivations, has already been done effectively once via Cell, and the current Super arc looks to be going down a similar path, at least in terms of Goku's positioning in the eyes of opposing universes. I wish the latter were being handled a little more coherently, but both those seem like better options for getting at the antagonistic angles of his personality. An outright evil, villainous Goku, pulling fully on the good version's personality and faults, doesn't seem like it could be all that effective or truly rise above its obvious gimmicky hook. Allowing Black a completely separate identity and motivation let the character carve out a fun niche.

But yeah. Black isn't Goku. He's a body-snatcher who became obsessed with him. Ultimately he's about as much "Evil Goku" as Baby-Vegeta is "Evil Vegeta."

[Freeza9000]

What honestly made Goku Black that great of a villain was because of how it showed Zamasu's evolution as a character and how much knowing Goku has changed him. By the time Goku bested him in a sparring match, learning how the mere mortal tapped into godhood in GodTube, and learning all about Goku through Zuno, he became disturbingly obsessed with Goku. He still obviously hates Goku for being the representation of the mortals' sin, but also developed a disturbing interest for Goku and his body such as when he relished every moment in fighting Goku in the past (whereas the original Present Zamasu felt quite uncomfortable and irritated fighting a mere mortal). Even to the point where Goku Black was at times influenced his the body's instincts when he admitted that his body wants to kill Goku (EP 57). Not to mention, inheriting Goku's Blood Knight characteristic of desiring to become even stronger than before through combat and inheriting Goku's calmness and exhilaration in battle. It's also worth noting how Goku Black's obsession with using combat as a means to boost his fighting power overpowered any rational decisions like Black using the Super Dragon Balls to wish for the extinction of all mortals or wish for immortality, similar how Goku's selfish decisions overpowered any rational intentions especially when Goku refuses to escape Namek and wanted to satisfy himself by beating Freeza at his fullest. I like the fact that this isn't a villain that happens to be an evil clone of Goku, but rather a villain with his own twisted ideology/philosophy blended in with some characteristics of our beloved battle hungry protagonist.

[TekTheNinja]

The fact that he wasn't actually Goku.

[Doctor.]

He's fun and interesting due to the fact that he mixes Goku and Zamasu traits, as well a the fact that the show never takes his ideals too seriously and is always ready to poke fun at his flamboyant personality. Also Nozawa. Take those elements away and you have a generic, boring, uninteresting villain like manga Black.

[dbs fanboy]

Because he's motherfucking Black (no pun intended) that's why.

Now seriously, it's actually a combination of elements.
1) His introduction, in ep 47 he straight out murdered Bulma, killed Mai (well we thought he did) and for a great part of the episode he was presented as a weird shadow, which gave him a more menacing look. Then when he attacked in the end of the episode he appeared covered by darkness, shooting ki blasts like a badass and when his face was revealed, boy was it dramatic. All this made him really an intimidating character and it changed a lot super's tone in that moment.
2) Mistery. We were expecting an evil Goku but we ended up getting soething completely different, in his way of talking, behaving and when he said "I've always wanted to fight you with this body", all of this left us thinking "Who the hell is this guy?" and in my opinion it was well done.
3)The fact that he's Zamasu made him better because it showed us a different stage of the evolution of the corrupted kai, and the fact that he respected Goku, the reason of why he got Goku's body (explained in #66) and the fact that his personality has changed since he changed bodies, made him great.
4) Masako Nozawa.
5)Being a badass.

[The gr]

He was a very unique villain in the DB world,he was flamboyant, always calm, very intimidating and his interaction with his good counterpart are endearing. And his entrance was epic and nozawa voice was just amazing,I don't see Sean schemmel performance being better than that,but who knows he might surprises us.

[SansrivaaL]

Anime Black yes, Manga Black no.
Anime Black worked because he's sadistic af, and the fact that him getting overpowered only gave him joy because he knows he will get stronger from that, I kept saying this but the moment FTrunks gut punched him and he laughed it off? instantly made me feel like he'll take us to a hell of a ride, but he blew past what I was expecting of him, really hated it when he merged with Zamasu, Merged Zamasu was generic af.
Simply said.... Black is 素晴しい (subarashii)! I miss the bastard, hence why I'm glad that Goku's being like this and add Nozawa's deep tone, we get Black 2.0!

[emperior]

His reveal, his speeches and his personality. He isn't a conventional Dragon Ball villain, and he was handled very well.

[Lord Beerus]

What made him work was the fact he wasn't an evil goku, evil goku is still an odd idea

Summed it up perfectly. Goku Black wasn't really evil Goku to even begin with. Goku Black was his own unique character with his own wonderful quirks. He was extremely sadistic, as well as savage in battle and also relished the opportunities to test his new power or abilities. But he was shown to be very pragmatic is his way of achieving his Zero Mortals Plan, never lost his composure when things didn't go his way and was also so formal with his speech pattern. And he never wasted an opportunity to display his superiority complex and his fixation on beauty. Plus, Nozawa fucking killed it as Goku Black.

Goku Black kicks ass!

It just make his characterisation in the manga all more disappointing. He's generic as fuck in the manga.

[apex_pretador]

Zamasu's disappointment with mortals was what made black (actually do) work (of exterminating mortals) but it were the superdragonballs what made Black work (as a character).

[Low Tone G]

In my view Goku Black didn't work, actually...

[omaro34]

His personality was unique, he wasn't your typical doom and gloom villain, he had a clear motive which was developed throughout the arc, and he had clear objectives.

[ChaosLordBrandon]

Black just had great execution.

[Lord Frieza]

I can only add to what people have already said, ite because Black was not an evil Goku in the greater sense although I disagree that there was nothing of Goku in there.

I stated during the arc, when it was revealed who Black was and some people were kicking off about it, that Evil Goku would be nothing like Black. Evil Goku can be done only two ways based on Goku's character...

1) Goku goes back to being Kakarotto - This idea is the most boring of the lot, why? Because Kakarotto would be a generic saiyan and we have seen exactly what he would be like through Turles. We've also seen it in Radditz, Nappa and old Vegeta. Goku would be a big bully with a might makes right attitude. We have already spent a whole arc and movie with the idea, we know what saiyans are like and Kakarotto would add nothing that we didn't already now about that race and there ideals.

2) Goku goes bad or insane - Again we have seen this befor, Cell, Buu and Broly are all good representations of this idea and an Evil Goku based on this idea would also be pretty generic as a strait villain since we have seen it befor.

Now people will ask why could an evil Goku not be like Black? Because Goku has almost none of Black's character traits, the only thing they share is a love for fighting and getting stronger. The rest of it, the twisted pride, smug attitude, sadistic nature and eloquent, upper class manner are things Goku simple dose not have. To have Goku, Goku of all people, act that way would require him to act so out of character that it is character breaking. Goku would never, even if he turned pure evil, act like Black dose.

Also when I say "there is something of Goku there" I'm referring to Black's battle lust, This was the single best thing to add to the character, the fact that while he is Zamasu in soul, some of Goku's saiyan nature is effecting him though the body inhabiting his body. Not only is it a great way to at least have some of Goku's traits appear in Black but is also allows him to act and think differently to his counterpart.

[Grimlock]

Goku Black worked because... He was given proper time (which is essentially what most characters need... Time), he was given proper development in some extent that Ginyu in Goku's body hadn't got it (which, again, is another thing most characters need... Development). He has his own personality, which differs from Ginyu in Goku's body and Turles. He has a cool design and has stylish techniques. He's somewhat unique even though he was seen together with himself, another Zamasu. I think those are the reasons why he worked.