If I were to describe Ajin in one word, then it would be: clever. If you like tons of plotting and creative uses of power reminiscent of Death Note or Code Geass, then you will very likely like Ajin. The characters are very relatable, and as long as you stick with the main character's selfishness for the first story arc, you will see him develop wonderfully as somebody who is rational and calculating, but at his core a very driven and caring person. All characters behave believably and have greatly complex motivations for each of their actions, and their subtle emotions are captured well by the mangaka. The sob stories aren't painfully drawn out and ideals they hold seem more in line with what real, driven people would likely have. Overall Ajin was a great read for me, and if you enjoy complex multifaceted characters and complex plots (great usage of the immortality power), then you'll likely love Ajin too.