Story
The story is quite interesting, and fairly original. The quality of its presentation varies throughout the series, however - foreshadowing, for example, is plentiful and very well intertwined into the story, so that little details that you might notice but not think much of turn out to be intricate plot points later on. On the other hand, there're the cheesy "OMG! The sky is falling!" bits usually associated with fantasy series surfacing all around the second half of the series which definitely hurts the suspense of disbelief. Another flaw is the climax being stretched into the last 3 episodes which could've easily fit in a single one.
Art
Not bad, but nothing to write home about. It's detailed and fairly pretty, but the sudden switches from ultra-contrasting (butterfly clouds, Hikari's hair and dreams) to ultra-pale colours (most secondary characters, slice of life sections) that happen every few minutes are annoying. The deformed butterfly logo is a definite plus though - very memorable.
Sound
The opening/ending songs are quite generic, but the last episode's ED is nice if only for the fact that it's meaningful in the context, which is a rare occurrence in anime. Background audio is hardly noticeable, but it completes the atmosphere well enough so that's good.
Characters
I'm a bit torn on this point. On one hand, the four main characters are very likeable and by the end I definitely cared about their fate. On the other, however, apart from Akari, all of the characters bring on a sense of deja vu; a reckless protagonist with a funky hairstyle, a troubled past and superpowers - check; a jealous childhood friend - check; a calm and popular big brother - check; a busty foreign drunkard who is actually wise and "cool" - check as well, and those 4 is just the icing.
Enjoyment / Overall
I've enjoyed the series, personally, but it felt like I had to go through all the silly action segments, plain stupid fan service, boring showcases of jealousy and unfunny jokes to get to the few excellent romantic scenes here and there. On the whole it was worth it, but it could've been much better if they didn't try to put in a little of every genre and concentrated on getting just one or two right.
