It's extremely interesting and my favourite show that we're watching currently on Thursdays (well, apart from Madoka, but that isn't at WAMS so I won't talk about that here). The setting is unique and something which you don't get to see in anime, the characters are all intriguing and the soundtrack is fantastic. Whilst some people don't seem to like the plot switching between years all the time and the fact that there's no real central protagonist, I find it a rather interesting way of displaying the story.
Also, Isaac and Miria might just be my favourite couple in an anime. They're utterly fantastic.