Animation - All around the animation in this movie is just beautiful. All the different visuals and ideas in this movie are just wonderful. This is worth watching just for the appearance alone.
Story - This is a movie that is full of brilliant concepts, but they don't all tie into each other very well. The pacing is all over the place. Maybe if the movie was longer or had a better script it could've worked better. The only version I could find was with the English dub, and not the original though. Maybe some of it is more interesting in the original and maybe the story flows smoother, but based on the length of scenes I doubt it. The story isn't terrible, just a bit disjointed and generic at times.
Characters - This movie is a bit light on the character development. It probably could've spent more time on developing any of the characters. Honestly one of the biggest problems with this movie is that it is way too short.
Glim - (this bit might contain spoilers) Glim is a character whose concept is more interesting than her personality. She is a person made of candle wax that melts when too hot and freezes when too cold. Its kind of a cool idea. The problem is, she is completely unnecessary. Glim combines two of the tropes I hate the most - completely bland an unnecessary love interest, and the fake-out death. She could've been removed from the story completely (along with those "comic relief" demon things) and nothing would've been changed. The only reason I can see for why she is in the movie is so that there is a female character. If the movie really needed a female character though then why not make one of the guardians a girl?