Hands down the most ambitious Atelier game. I'm not a fan of the writing, but the way simply exploring the world forms a narrative around Firis' dreams and such manage to move me. The happiest an Atelier has made me. I think that says a lot.
I think it's too simple for it's own good at times, but I still remember the ideas in it. Still gotta embark on the full Exa_Pico journey, so I can't wait to these ideas develop. やがて錆びた剣を囲んで緑の蔓が這う悲しみの記憶を包んで is one of my favorite lyrics.
Shuichi is a very compelling protagonist on his own, and the way he hates solving crimes repeatedly being used against him and seeing him overcome that is moving.