The biggest gripe of reworks that make them considered failures is more so of the attitude and lore changes.
Galio was complained mainly because of his attitude changed. He went from a unqiue stoic guardian. Always prepared, vigilant, and guided while giving advice. He would tutor Shyvana to control her rage, Poppy in confidence and to move on from her tragic past. After his rework he was mostly compared to that giant jerk, or some compared him to Jayce. Jayce isn't a bad character, just why have two same attitude champions. I personally like the rework, he should be a Vanguard and not a mage ... warrior ... thing. He is more active in melee combat instead of a sniper. I can see the complaints in changing play styles.
Swain was hated entirely based on looks and no Beatrice. His kit on the other hand, was considered perfecto by all, haters and lovers. His attitude, voice, everything else was good, it was his design that was considered a complete failure. It is the fact that he went from an old crippled man, with a walking stick and a six eyed bird, to a somewhat old muscle bound man with a claw hand like thing and no bird. People compared him to Vladimir, and considered he stole Vlad's rework. He even looks a bit like a older Vladimir with his hair style a bit matching. I personally agree, Swain was unique, even to his hair due. Now he is a copy pasted muscle mage, that seems to be the new fad these days. I prefer my mages and warlocks old, withered, and weak, but crafty, clever, and wise instead.
However of all the reworks that are failures, Aatrox takes the cake and cries while eating it, absolute worst rework unchallenged. His rework makes the Juggernaut rework, including Morde, look successful. Everything that was Aatrox is no longer Aatrox. The only reason he is picked is because he is an early game power house who drops off just as bad as Pantheon, but is all better. This is an early game meta so of course pick the best early game champion. But that is the thing, old Aatrox was an auto attack late game destroyer when he got there. His revive was a late game changer that turned the tides when it was being used well. Auto attacks are also the best late game.
Still continuing on, Aatrox's looks and lore are even worse. His old looks were jagged blades and armor, with a darkened, look to represent destruction and death of WAR. Now he is smooth and mostly red, looking like more of a plastic toy, what a joke. His lore rework destroyed League of Legends. It changed from a LEAGUE OF LEGENDARY HEROES FROM ACROSS THE PLANET AND COSMOS to League of Lovecraft. The Void is the big bad, what about the Shadow Isles? Or the Frozen Watchers? The Shadow Isles will probably turn into some innocent anti hero group or something. The Frozen Watchers even got retconned into the leaders of The Void, such a terrible shame. This is the same mistakes WoW made, changed a unique lore into just another Lovecraft story. Always happens when Lovecraft is involved.
But it doesn't even end there, now for the worst part. So Aatrox's kit, and looks are completely different, but what about his attitude? Horrible, absolutely horrible, I mean AFFECTS YOUR HEALTH HORRIBLE! Whoever in Riot thought it was a good idea to make a champion seethe, whisper, rage while yelling, what have you about wanting to commit suicide and hates all life a good idea ... that person should be mentally checked. I think that person wants to commit suicide and should be helped not to do it. Listen to old Aatrox's audio file, you'll hear an awesome, fantastic, professional Demon God of War at his finest work. He had the best voice, attitude, and lines, no other champion could even be close to compete. Now he is a suicidal depressed emo bitch, to which again, wants to commit suicide. I sometimes have to take breaks from the game after playing him because he makes me so sad and super depressed from just listening to him. I could just mute him but that doesn't really work.
Phew long winded rant there haha, Aatrox rework was a personal one. Also before I forget the man behind Aatrox's rework stated that the rework was NOT for Aatrox's mains. ... Then what the f%$k is the point of a rework for then?