I watched the first episode mostly disliking the show. The art was really bubbly and shiny and one of the center girls, Manaka, was an annoying, whiny klutz. To my surprise it actually got alot better. The characters get developed and some interesting dynamics get added to the story. Not only that, the visuals they kept consistently very high quality made it easily the prettiest show of the recent year I'd say.
Now don't get me wrong, despite this being a world where there are people living both under water and on land, thus sporting a other-worldly element, this isn't exactly it's center point. It mostly serves as a backdrop to a complicated love pentagon between the main cast of kids with plenty of melo-drama and tears (which the story around them just pushes further).
If you're into romance give the show a go but don't expect the biggest mystery out of the legend of the sea god here.
By the looks of it the next show of P.A. Works will be pretty much this again so let's hope they manage to top this.