Personally I loved the story. It is well written to pull together action, mystery, humor, and even some feels. It is not particularly unique and is full of the typical anime tropes that most high school setting's entail. Additionally, the show starts off by giving you too much information, and hoping that you'll retain it all by the time everything starts to make sense. However it is one of those stories that gets better and better with each episode. From episode 4 on, the shows momentum cannot be stopped, and even the flashes of backstory are well placed and only serve to improve your understanding of the plot.
The characters in this show were easily the strongest element not provided by the production studio. Despite the small episode count, K included at least a dozen intriguing characters with the only major flaw being that we couldn't see more of them. The writers foiled characters to each other and provided just the right amount of backstory to develop several major players far more effectively than most 13 episode anime.
There is not much I can say about this soundtrack that would do it justice. It is beautiful. I believe that anyone who watched nothing but the first 30 seconds could not honestly deny the quality of the music. Not only is it stunning, but it sets the tone for the show as a whole, and makes an ordinary scene come alive, while augmenting the impact of the more emotional scenes.
The art is stunning as well, rounding out the incredibly positive impact the studio (GoHands) had on the quality of this anime.
Ok, I added in another category below where I justify any other positives or negatives that wouldn't perfectly fit into one of the 5 categories provided. For example, I was incredibly annoyed by a few of the minor plot devices between episodes 2 and 4. I would also point out that many of the interesting characters were not fully developed in K, which was bothersome, but were developed in the second season. Finally, one of the main characters I found annoying as an overdone archetype who is used primarily as fanservice. (And I didn't want to factor her into "characters" because I felt it would not do justice to the others to include her in my number)
Story: 8
Characters: 10
Sound: 10
Art: 10
Enjoyment: 9
Overall: 9
