Ajin is quite a bit of a mixed bag in quality, but I shall focus on the positives to the series first. The series does a solid job with fleshing out the capabilities of the Ajin as such where characters utilizing their abilities like Kei and Sato are able to analytically plan out how to use their abilities and work around their limitations, including occasions where they commit suicide to fully recover themselves in the event of injury. The series also offers some surprising twists and fleshing out of its plot for later episodes regarding the mentalities and motivations of major characters, notably with Kei and the government worker Yu Tosaki. Also, the show's animation is quite fluid with engaging action sequences and great cinematography employed during some key scene points, this shown most notably during one of terrorist operations committed by Sato and his group.
Beyond these points though, Ajin does come with a fair number of major issues. The show's direction on being a dark and cynical world is a bit too much on the heavy side and can come off feeling forced, especially with how many humans in the series regard Ajin. This is most evident with major characters like Kei, Tosaki, and Sato who all have cynical outlooks on life and make morally questionable actions for either their own self-gain or advancement of goals. In spite of the great fluid movement by its animation, Ajin's use of 3DCG animation in a style similar to Knights of Sidonia does make its character designs look artificial in their appearance and their movements can usually look unnatural compared to how the IBMs get rendered. Also not helping matters is the series ends at a rather major point in its storyline that appeared to be deliberate in setting up Ajin's second season.
While Ajin does have some engaging story elements and twists, its attempt at painting a dark and cynical mood felt forced and its key characters were hard for me to care much for. While your mileage may vary with how you warm to this series, I don't see myself being invested enough to venture into Ajin's second season.
