This review will contain non-explicit spoilers.
Akuma no Riddle is an anime which I looked forward to viewing every week. It is an overall enjoyable experience if you bear in mind the short running time. I personally found the end disappointing, however.
Story - 6/10.
I enjoyed the premise of this show - a kind of Danganronpa-esque survival game within the "Black Class", a class of 13 students. It wasn't totally butchered; there were some interesting plot twists here and there and the pacing was okay for such a short anime, however because of its shortness, it did feel a little rushed at times, for example some of the battle scenes could have been expanded on a little more, and similarly to Danganronpa we lost a character per episode on average, which didn't allow the watcher to fully connect with the story.
I also did not enjoy the ending. I don't understand why the show went through killing them each episode for that to happen at the end. Maybe I missed something.
Art - 8/10.
Decent character design, I enjoyed the animation generally. Thought the battle/action scenes were eye-catching and didn't leave you wanting.
Sound - 7/10.
I really enjoyed the soundtrack to this, Soushou Innocence by Maaya Uchida fit the theme of the show relatively well and set up a mostly fast-paced action-filled episode each week. The voice acting was good, the only voice that really irritated me was Haru's, but that's personal preference as opposed to bad seiyuu. I thought for the most part the voices fit the characters.
Character - 5/10.
This is where the show tripped itself up a little - though this is mostly due to the short run time of the anime, only 12 episodes. Each character was relatively unique from one another, though I didn't think any character really screamed originality this didn't really detract from the anime as their interactions were still interesting.
However you never really get any chance to get attached to any of the characters, their backstories are briefly outlined but because they tend to disappear rapidly we don't get a chance to root for anyone, to really appreciate why they are here and why they became an assassin.
The relationship between Ichinose and Tokaku was never properly expanded upon, which is a shame, it would have added another dimension to the anime however this again suffered from time constraints.
As a result we get quite one-dimensional characters with no chance to really learn about what their true motives, drives, etc are.
Enjoyment - 8/10.
I did enjoy this anime, although the last two episodes left me with a "meh" feeling. It looks and sounds good, no glaring errors there, and the story itself is a good watch, and it does get quite gripping at points.
I would recommend this to those who like anime which will have them on the edge of their seats at times, however don't expect a masterpiece.