It's just that when you like something you can't help but also feel frustrated with it at times.
I think this really sums up my feelings on the matter. With Oshi No Ko I feel like for every two things I like, there's something I dislike or think doesn't make sense.
I like Aqua's constant critique from Crow Girl being that he doesn't have the will to kill his dad.
I like the small details that Aqua is still studying for a life after a revenge plot indicating that he doesn't expect to be dead or in jail.
I like that the revenge plot was just to force Hikaru to know that he played a hand in destroying the one person he ever cared about, and if he hadn't done that, she had extended him an olive branch that might have given him the life and love he'd been cheated on, and that, that ultimately breaks him.
Unfortunately:
I really dislike that despite all the good elements leading into Aqua's revenge, it still feels rushed and cheap somehow.
I don't like that Hikaru's character is as sympathetic or evil and the story needs him to be at any given time. Sometimes he's a serial killer. Sometimes he's a victim of molestation who's just been damaged. Sometimes he wants to kill his kids. Sometimes he seems like he really likes them.
Nino exists and is apparently super relevant to everything despite not really being mentioned until the last arc.