I made sure I watched it until the end even though I wanted to die, so that people would not say that I hated it just because I missed the best part.
It was crap from start to end, they took a nice idea about a fantasy world that could totally become decent and turned it into the most senseless idiocy about "love", a kid's fairytale with no goal whatsoever.
The best ideas such as enviroment and history were completely skipped and left unexplained, the setting under the sea could become absolutely awesome and they botched it, because instead of adjusting it to the situation they simply stuffed a copy of a normal village on the bottom of an ocean with no change at all. They even have stairs. They drink broth. I just don't understand what was the point of such a forced setting.
There are loads of things that I don't understand, but just to say a few: why in the world do people from the sea and from the shore hate each other so much if they don't differ among each other in the slightest? They have the exact same culture and habits, they eat the same stuff, they even put the same designs on curtains; Why the hell should salt fall from the sky? I'm fine with fantasy but you could at least try to come up with some kind of explanation; Did someone tell those guys that they didn't have to go as far as to make every possible pairing? There are fanfictions for that; Just where did the other students of the sea school go? That's kind of creepy, they simply melted away, right?
Oh, and yes, I totally agree that the series did a 180 turn. The characters visibly leveled up in annoyance.
The ending was the best part of them all, it just wrapped things up as uncomprehensible as they were and gave it all that sickly sweet taste that dulls every black hole in the plot to a triviality.
The dialogues were awkward, trite and embarrassing to listen to.