I can kill any other assassin 1v1. I mean in absolute terms. While other assassins slipping up can get you out alive.... like getting out of a Zed ult before he does enough damage to kill you... or Zhonya...... Akali can literally 2 skill you and there isn't a thing you can do about it (even Zhonya, because her Q has such a low cooldown, and her second R can make up for missing the first one)
About the only other assassin who can do this is Talon, and he does so at the risk of being out of place, having less away from wall mobility, and dying easily.
I brought up Karma specifically, because her kit counters Akali's (even in this form). If you can tether her with W, you know where she is in cloud. Her self heal on W also counters big chunk damage. And her shield. I'm a 4.8 million mastery Karma player. I couldn't stop her from killing me, because that's how much control she has over a lane.
I've played the new Akali, and although I haven't got good with her yet, I get the gist of why you might want to defend her. As an Akali player, you really have to learn to be patient and economize your energy levels, since Q takes half your energy bar and her only way to gain extra energy is her E (which is basically an energy REFUND, since E costs 30 Energy and crossing the boundary and coming back only refunds 30; You can also get energy by using her R or move speed items, but that requires significant mastery of her to exploit)
From an Akali player perspective, I'd probably agree that she's fairly balanced (albeit her whole kit can 100-0 2 people before she runs out of energy if played right). But from an opposing player..... no.... she's broken as hell once people master her. She's more toxic than Yasuo. It took them 2-3 days to turn her into a 3 KDA monster. By 200 games, these Akali players are going to be pushing 10-12 KDA's regularly with her current kit.