Most of the reworks came out fine.
Sion went very well. He was a mess before but what he does as a champion is very clear and he does it well. He won't change the meta. But it was overall a success.
Viktor's went very well. People disliked that he was always picking the same item. Now that item has a lot in it for the slot and he gets a lot of utility. He gained a lot and really only lost his silence.
Soraka overall improved. The fixed the issues she had while keeping her image.
We don't talk about Cassiopa
Sona's was well done as their aim was to remove her hidden power. And she can play different ways now. Staying in the fight means she can use her aura's for the team better. Staying back means she can play safer like she used to, but doesn't give her team a bunch of free stats. IMO well done.
Skarner I've heard different comments. I don't think much about him has changed overall. They just made him more like Hecarim. Overall i don't have room to talk as I've hardly touched him and he's still rare to see.
Nidalee overall an improvement. But they still can't seem to get her numbers right.
Rengar overall an improvement. Ended up not mattering really once people learned they could still instagib ADC's. But he has a more secure place in the game. Even sees pro play now.
Gragas was a one of the better updates. They made him exactly how they wanted him. And he gained a lot of flexibility in rolls and lanes with that.
Kassadin is overall healthier for the game. Still a pita though.
Hiemerdinger was a great success. IMO everything about him improved.
Xerath's update was a success. But they did hurt his image as a champion. But it is understandable why they did what they did. Being able to WRERQR and easily destroy targets with little room for retaliation wasn't healthy.
Sivir was improved. Although they could undo some of her previous nerfs. What made her strong at that time isn't as much of an issue anymore.
Olaf... is Olaf. Just make him manaless already so he can eat ranged in top. (Attach his W's lifesteal to his ult like Sivir's W's AS boost is on her ult)
Mastery Yi was a success.
Trundle I don't know much about, but my understanding is that he didn't really change that much. But he does see more play. And seen in pro games.
Sejuani overall similar to Skarner. But I do know she was Op for a while after the rework. But she was never really weak to begin with. She just couldn't survive the jungle and be useful to her team early enough that S3/4 junglers were heavy on.
Karma's rework was a success. Like Xerath she got her image hurt quite a bit. But is overall healthier as a champion. Honestly if they found a way to keep the shield bomb they probably would of gotten much less hate. (Make her RE deal 1% bonus damage for each 1% Hp the main shielded target is missing, this still deals less damage than RQ btw.)
Gameplay updates before that are from before my joining League. Most of the reworks Riot has done are successes.
Sej/Skarner's problems mainly are the jungle. Both are monsters in teamfights and will put out a lot of CC and damage.
Nidalee just overall has a toxic kit. Maybe if they just removed the heal? Don't think that would really fix her, but it may help punish bad mistakes.
Olaf needs to be manaless. limit his lifesteal so it's not OP in lane, limit his Q'ing, but not enough that he's punish if he has to use it farm.
Changes
Rework
Rework
Rework
Rework
Rework
Rework?
Rework