Well there is still a little nudity, it is maybe a little more brutal than season two and there is more death for characters from season one and well no one stays human.
Song Kang's perfect long hair will be gone, but in exchange we have his blue eyes, still happy about it. Yes, chemistry between him and Go MinSi is still killing me - I would love if they made them official but what we got is still satisfying enough, especially when it is not a romance type of drama.
We have Lee Do Hyun's character back. And suprising a happy ending ( a little open ending but in my opinion still a happy one).
Would I like if it had more seasons? Probably yes. Do I like how it ends? Yes.
If I had to rank seasons it would be season 3 = season 1 > season 2, but still for me every season is as much good so they have exactly the same rating: 9/10.