I've watched some AJin a while ago and it's pretty interesting.
It had some pretty good concepts that were nicely executed.
Now i don't normally watch 3D anime but this one was pretty good, the 3D models were pretty nice as well the scenery and areas, the weapons also looked pretty nice as well the effects. the idea is also pretty good, even though the whole concept of immortality has been done like a million time in anime, movies, books, comics, etc, this anime did it in a pretty cool way unlike how some other shows make immortal characters unharmable, in this anime however, the characters actually get hurt but regenerate and show some signs of pain unlike most other shows where the character becomes immune to pain in all forms and doesn't even show a slight sign of being hurt.
I recommend you guys give it a watch.