Sorry I am bothering you about such an old post but could you tell me how you feel about the manga now? I started reading it recently but I heard that the quality starts declining around halfway through. I'm currently reading the first chapters of what I assume is the music video arc. And why did you hate Akane? I like her so far. I don't mind spoilers.
Sure, no problem.
I didn't really notice a decline in the story until the Movie Arc and the decline is frustrating because it feels unnecessary. Essentially throughout the story narration is provided either by Aqua or Ruby. It keeps you focused on what's happening, explains how the various industries work, and keeps you routed in what's going on and what the characters are thinking, why they're thinking it, and what their plans are.
In the Movie Arc you get no narration from either person. Shit just happens and it is often ignored for dramatic effect and you don't actually see how your favorite characters respond to it. This doubles as frustrating for people because a lot of big reveals happen in here. The biggest being that Aqua and Ruby finally realize who they were in their past lives. Its after this that Ruby makes a very controversial move on Aqua and kisses him which got the anime labelled as an Incest anime because not only did this happen, you don't actually get any of the character's PoV on it, which is only made weirder when like the chapter before the anime was crucifying pedophiles and loli enjoyers as sex offenders.
However at the very end of that Arc you do eventually get Aqua's PoV as a former doctor and he sort of in one chapter sums a lot of shit up. He's not okay with Ruby's behavior, he understands that she views her current life as an extension of her past life and that she is the same person where as Aqua views himself as having been a doctor, died, and is now a completely different person with completely different circumstances to the point that he even considers his past life something that will fade with time and be nothing more than a nagging instinct he had when he was younger.
As to why I hate Akane. Akane is a very good character actor and does a lot of psychological work to imitate people perfectly. She figures out earlier than anyone else that Ai had children in secret and that Aqua and Ruby are those children. In the immediate next arc, she realizes her rival to become Aqua's girlfriend is Kana Arima and worse yet she realizes that Aqua is essentially head over heels for her. Rather than just accept defeat and move on, Akane decides to do the most mentally ill and manipulative thing by telling Aqua he has to stop seeing her, because his mother had a boyfriend and look how that went for her.
This causes Aqua to refuse to act on any of his feelings towards Kana out of literal fear for her life and instead settles for Akane, who knows he's settling, comments on him settling, but considers it fine because she got her way. I have known women who would do that shit in real life. It sets my teeth on edge, because those sorts of people, male or female are fucking dangerous.
**EDIT**
I got to work and realized there was more I wanted to say about Akane and why I don't like her. For instance a thing happens where Aqua believes that his father has been dead for a long time and allows himself to start to live a normal life. Akane figures out early on that there's something Aqua missed and that his father is still alive, and then decides to not tell him, and attempt to murder Aqua's father before he can get a chance to.
This is what ultimately kills their "relationship" because she just decides that she's gonna steal Aqua's one goal he has, lie to him about it, and then literally commit murder. The bitch is absolutely cracked.
I also wanted to expand a bit more on people's claims the quality has gone down in another way: I think a lot of the claims come from people who are too invested in the shipping wars.
Most of the fans want Aqua to end up in a relationship with Kana, Akane, or if you're a gooner faggot Ruby. They have made years of head canon justifying why Aqua should be with whomever they pick and often ignore important details in the story to justify this. Then when the story doesn't go their way they get very angry.
For instance, Akane's fans often scream and bitch that Kana has done nothing to deserve Aqua liking her and that its bad writing. However they are happy to ignore that throughout the entire story Aqua has just liked Kana. Its not more complicated than that. They get along, they're attracted to one another, and he just likes spending time with her. They don't need some dramatic show of affection that "wins" the ship war or whatever, but because those tropes haven't happened, a lot of the fanbase is very fucking angry.