A lot of people immediately refuse to watch stuff like ajin, simply because it's made with 3D animation.
And while i also prefer 2D over 3D, this really shouldn't factor too much into how you view a show. It can't be avoided however if possible try to look past that. Ajin is a show very similar to parasyte and tokyo ghoul.
It's the kind of anime that pits two sides against each other, and makes one of the sides opressed. Ajin does something quite weird however, it takes the focus a little bit away from the main character, and focuses more on the supporting characters.
While the main character is still very important and relevant to the story, a little over half of the first season focuses more on building up the scenario and giving information. Now this is clearly not unheard of, actually it's quite normal. but a little different from, say parasyte.
The story of ajin is like i mentioned very reminiscent of stuff like parasyte. It's not unheard of, but the physical abilities of the ajin make the story quite a bit different from parasyte, I'm not saying this is either good or bad, just different.
The art is probably what puts most people off from watching this, but if you're intrigued by the story, don't make the art put you off.
The soundtrack is not easily noticeable, there are a few good ones here and there, but not something of great significance. The opening however, is in my opinion really good.
The characters are definetly one of the series' strong points. This especially goes for nagai and satou. Nagai is a very interesting main character as he's not a bad person, but not a good person either, more of a neutral ground, which i think was actually a very good decision on the authors part.
As for overall enjoyment, I won't say it's one of the greates anime, but i still enjoyed it, even with the 3D animation.
Overall, what i have to say about this anime is, don't let the 3D animation put you off, at least give it a chance. Also if you're a person who likes parasyte or tokyo ghoul, I highly recommend ajin. However, if you really can't get yourself to watch 3D animation, then don't bother
This was my first review, so a lot of it was just me rambling, I hope you don't mind