5.1/10? You are crazy.
This was an 8 to me.
The reason it gets voted down is fandom for the Anima/Manga version. People who are obsessed with one version of a film/tv show can never properly judge other versions, this would have gotten a lot of 0/10 from them. It was the same with The Last Airbender.
I never read the comics or saw the tv show so i can judge this for what it is and it was excellent. The Titans were really scary and fascinating to look at. The dark grim world was compelling and the characters were good.