It's hard to say that Akali's rework was an overall failure - she's hitting 12% playrates across pretty much every tier, she sells skins, financially she's a success. Her presence at worlds also plays to her being strong.
So instead, we're going to attack this issue from what most people are complaining about - her gameplay. But while she's certainly not a fun champion to play against, you could still say she's a success because maybe that was the plan. Except for one glaring issue:
If we go off of what players wanted fixed about old Akali, this rework addressed pretty much none of the issues while exacerbating several of them. Those issues were:
1. Akali did not exist in lane before level 6, pretty much just trying to sustain and farm with her Q and passive.
2. After level 6 Akali became insufferably overbearing to the point you pretty much couldn't get her away once she latched on to you.
3. Akali had a tendency to faceroll her way through low elo games with her low interaction and low skill-ceiling gameplay (similar to Fiora).
4. At a certain point, Akali would often get stonewalled in teamfights by pink wards and AoE damage, making her a liability come late-game.
While I'm sure some Akali mains could probably list a few more grievances they had, these were the big 4 that I recall from the discussion on her. With those listed, let's go into just what the hell happened with each one of those points that Riot had claimed they would address:
1. Akali now very much exists before level 6. Good job on that - the issue being she's a fucking nightmare against any champion that doesn't just grossly outrange or counter her. While she could certainly harass you with her Q before, it did bug-bite damage unless she was brave enough to walk up and actually proc secondary damage - you could practically ignore it. Now, not only is the cooldown much lower, but its damage is all front-loaded - so if she hits you with her Q, she's hitting you with the full extent of her damage. This is ignoring that this activates her passive as well, which gives her an extra reward for hitting you - except now there's not really much risk to proc-ing that in lane as she gets a speed up _and_ her range is extended on the auto. While I wouldn't find much of an issue with this if I'm playing a champ like Lissandra that can just smack her in the face with multiple punishes every time she wants to come up, not every champ is Lissandra, and many don't have any tools to interact with this excessive harass. Her level 6 overbearing-ness has, incidentally, been shifted directly into her level 1-2.
2. And with her overbearing-ness being placed in her level 1-2, I'll leave you to do the math on her level 6 - because Akali comes with not one, not two, nor even three - she comes with four total dashes. So while old Akali could just keep gluing her face to your ass every time you wanted her to go bother someone else, her new kit brings that lovely issue along as well with a plethora of additional speed-ups and one more dash just for good measure.
Now, where old Akali was better was that her dashes were all targeted - Akali needed an enemy to dash to in order to go flying away, which meant once Akali put herself in a situation, she had better hope it was favorable or she was going to get her ass played like the bongos. While this seems frustrating for someone playing as Akali, it pretty much just stressed that she think about if she should go in or not - but new Akali's dashes, besides the second activation of her E, are not targeted. This means she can go wherever, whenever - meaning now Akali not only has a way in, she also has a way back out, so not only can she stick to you like gum in hair, but she can freely dip out any time she thinks it's not going too well for her - and good luck catching her after that because the only other champion with as many dashes as her is goddamn Riven, and that should say enough on that topic.
3. Akali actually doesn't faceroll low elo games anymore because she's too busy facerolling high elo ones - while I can no longer call Akali players low-skill trash that don't even deserve to lick the dog crap off the underside of my shoes (like, no offense guys... but fuck your bullshit dashes back then, god damn), her kit is so utterly overloaded that in high elo games, many champions simply can't deal with her in lane, and thanks to the relatively limited supply of pink wards, dropping one in the middle of lane just to reveal Akali (who would probably just end up dashing away anyway) isn't exactly gold-friendly, and neither is sitting around for five and a half seconds waiting for her to come out of her goddamn shroud. Ganking an Akali is such a drain on time and resources that unless she's straight up just diving turret, you might as well not even bother - and higher elo players know how to utilize these exploits far more. So what we've done is pretty much just flip Akali around from what she was - instead of a low-skill low-tier stomper, she is now a high-skill, high-tier stomper, except she still has no fucking interaction because whatever damage you deal to her in lane she's bound to just heal it back up off her sustain. So the problems didn't get fixed - they just got shifted to an entirely different tier.
4. **BUT**, and like your mother's this is a big "BUT", her winrates plummet if the game starts going long - so when I say she stomps games I mean that game has to actually be a straight curbstomp or she is significantly less likely to win. Ironically, her problem of pink wards was fixed on release in the most utterly toxic fucking way imaginable (holy shit, who legitimately greenlit "true stealth"?), so that got rolled back - which just gave way to what we have now, which is **the same fucking Akali as before getting slammed in teamfights.**
And that's just it - Akali has pretty much the same exact issues now as before, but exacerbated to a frankly egregious degree. While the elo she's most problematic in has been flopped, she is still a) stupidly overbearing b) easy to zero-interaction your way to a snowball victory and c) a liability in any game that runs long, but now she is also d) horrendously toxic to try and deal with as a laner at all stages instead of just at level 6 and e) disgustingly safe with the amount of escapes and tools she's given. She is basically only in as much danger as the person playing her wants to be in, and more than any other champion she can pick and choose whatever fight she wants to go into however she wants to go into it.
In short: Fuck this rework.