Riot worldbuilders, Viktor's new lore is in fact really bad. This is why
I too initially thought that the new lore was alright – after all, it didn't say Viktor's a saturday-morning cartoon villain; I was taken by the reaction of the people who read it the first. Several months later, now, I can say with certainty that the new lore actually destroys this character. Please read everything, or skip to tl;dr
Legend: text written here is referring to the new lore. Old lore is marked as "originally".
The personality-changing
"Viktor was censured for violating basic human dignity" – the way the new lore is written, Viktor indeed did violate basic human dignity. Controlling someone, for whatever reason, is immoral. This is what makes Viktor a villain. Sure he doesn't cackle and twirl a mustache, but this is the biggest red light possible. Originally, there was nothing saying Viktor's work was malicious. All we ever knew was that it was groundbreaking and that it had the potential to change the world. More about this in the last paragraph.
Weeks of depression – whoever has this condition knows how it operates. And it certainly does not last for weeks, it lasts for months, maybe even years. Viktor's depression in the new lore was downplayed to the point of ridicule, as he wasn't affected by the theft of Blitzcrank, not even by the countless deaths of Zaunites, some due to his own work, but due to being expelled from some haughty Piltie college. Viktor used to be a character who got struck by injustice, who fell into such deep depression that the only thing able to pull him out was a complete change in the way of thinking. Originally, he never had ideas about human augmentation before surviving a tragedy. The new lore makes it so that he always had ideas of human augmentation, that he always thought humans were inferior. This is not the character he used to be.
Important things – in one part, we are told he now didn't dwell on Blitzcrank's theft because he understood how other things are more important. But then, he gets shaken because he got expelled from Piltover. "He saved many lives with his technology". Alright, but we're never told why. If he thinks humans are inferior, it makes it seem like he views people only as constructs which he is to improve. And he certainly acts this way, because he's much more shaken when he got expelled than when his patients die. This is psychopathic behavior, and it was never present in the old lore.
Chem-slaves – "Viktor did indeed send etc." it doesn't matter why he sent them. They were brainwashed, and they were equipped to kill. They would have killed the little girl if Jayce wasn't present. It doesn't matter how many lives Viktor saved in the new lore, when he's just as ready to take them away and/or control people however he sees fit. The old lore never said he controlled people. In fact, some Rioters even confirmed that in the old lore his followers were willing Zaunites who believed in the future he was working to build.
Many issues stem from the merging of Piltover and Zaun. This action, I would argue, actually limits the narrative instead of expanding it; instead of two technologically advanced cities, you have one, with less space to fit characters in. "Subcity" could have easily been Zaun's slums or Piltover's slums, and you'd have much more diverse options. Not to expand on this now.
"Friendship" with Jayce – Jayce is a character that basically started existing only thanks to Viktor. Why hasn't he gotten a lore where he gets expanded as a character, getting other enemies / goals in life? That would have been fair towards his character, instead of having it reduced to a typical hero jerk. Not only that, but now instead of Viktor being his own character, the new lore forced him into being dependent as a character on Jayce in return. This issue is the consequence of the forced symbiosis between the two cities. "The two were equally matched in intellect etc." - this is a completely pointless addition, and puts emphasis in Viktor's character on a "rivalry", instead of keeping his character's focus on his own spiritual metamorphosis. "Friends to enemies" is an overused trope, doesn't fit here, only reduces Viktor's character. If you really wanted to use it Riot, you could have, you know, made new characters for it!
Expelled from Piltovian college – which two characters went to the same college, with one getting expelled thanks to the other due to his "amoral experiments"? Doctor Doom and Mister Fantastic. Why were Viktor and Jayce pushed to resemble these guys in more ways than it's necessary?
Zaun's college of Techmaturgy – it's an eyesore how it was added just for the sake of keeping something resembling the old lore. It could have been straight cut because it's not relevant at all – Viktor got offered scholarship there and in Piltover, and he went straight to Piltover. Gee, I wonder in what way Piltover isn't 100% better than Zaun.
Expelled vs Withdrawn – expelled for his amoral experiments. I'll get to this in the last part, but being expelled has a completely different effect on psyche. Originally Viktor withdrew from the college because he was so hurt. Nobody gave a damn about him, nobody cared he had withdrawn. This resonates with readers. Being expelled from a college in a different city, which looks down upon your people induces hate in a character. And Viktor was never about hate.
Blitzcrank's sentience – Originally, Viktor and other students in Zaun created Blitzrank and his sentience. That's amazing! Why was it changed now that Viktor didn't create his sentience, that he wasn't even able to replicate it? Why was his intellect decreased? So that Jayce could catch up to him because they have to be equal to hint at the "symbiosis between the cities"? Also, sentience is not the same as intelligence. A self-improving robot is the example of the technological singularity, a turning point in history with unfathomable consequences for the human civilization. I'm not sure you even knew the meaning of this Riot. It was unwise to use it here.
Viktor's mask – I found somewhere... that supposedly, nobody even of the Riot's writers now knows why Viktor wears a mask. I know, and every person who read his old lore carefully, knows. Viktor was hurt, and the human face represents weakness. The mask is his shield, as well as a symbol of his philosophy.
The illogical (Some of these are nitpicking)
We were told that all tech now in the new lore is crafted by few very skilled artisans. But colleges for techmaturgy exist. Colleges mass-produce experts.
Viktor named his creation Blitzcrank – Blitz is a German word meaning lightning. But Viktor speaks with a Slavic accent, not a German one.
The new lore says Viktor's inventions became widespread in Zaun. Number of accidents in a forge that used his designs, fell to zero. Yet, Zaun is still a toxic hellhole in which every day countless people die due to accidents?
Viktor saw the human factor as a weakness, yet he tried to replicate Blitzcrank's... human factor.
How did Pididly now steal credit for Blitzcrank if he was in Piltover, and Viktor both created and left Blitzcrank in Zaun? In the old lore, Pididly used to work in the college of techmaturgy in Zaun where Viktor created Blitzcrank; that was logical.
Viktor created a chem-shunt helm for mind-control. He also engineered chem-slaves. But Viktor is not a chemist.
Viktor now seals his own skin over artificial prosthetics. Not only would it be impossible for skin to stay alive, skin provides no benefits if everything below is artificial. The same issue is present in the short story "Progress day" if I'm not mistaking. There's a woman with "artificial elbows" mentioned. As I'm pretty sure Riot didn't make it clear that now humans in the new lore are made of magical marshmallow, I'm going to assume they work the same way real humans work. Everything below that woman's elbows would have rotted and fallen off.
Viktor keeps organs in jars in his flat. Why? Well I guess for "aesthetic". He's not a biologist, I don't know why he'd keep organs in liquid preservatives displayed.
The worst
And here we are, at the last paragraph. We all know that in trope-y fiction, augmentation is always evil. Viktor used to be special in the old lore exactly because his augmentations weren't presented as evil. They were presented as something that could change the world, and were left to the reader to decide. Our own real world is adopting augmentation, which is improving lives. But... the new lore makes it obvious that it views Viktor's augmentation as evil. It brainwashes people. It kills people due to side-effects. Blitzcrank left because Viktor's tech killed some people they were trying to save. "If you're desperate, you go to Viktor". This has such negative connotation that it pains me. There is no trace of the original character who was a naive young man who believed in the goodness of humanity. Who got conned, then pushed off the edge into an extreme attempt to improve humanity as fast as possible. I have a friend who I know loved Viktor's old lore. It had given him strength in his darkest hour. It continues to inspire me. Viktor should have been Nikola Tesla of League of Legends – someone ahead of his time, feared during his time, but someone who would possibly built the future, and improve the world. I would pay for the new lore to be rewritten if I could. Riot, do you ever acknowledge, at least internally, when you make a mistake in the lore? Go over the points, see if I'm right or wrong. It took me time to shake off the initial impression I had because some readers created hype. Now all of my points are painfully obvious to me.
TL;DR Viktor's personality was changed in the new lore, he's not the same character as before. His work is presented as malicious. Old lore didn't present it as malicious. I gave examples and explanations.