Never saw or knew about the video game...but...
Now I wish I had...I'd like to compare the two. But I saw the movie on Netflix.
I've read other reviews, and I have to pretty much agree with them all.
The story is beautiful and amazing, it's the graphics and editing that most people have a problem with.
My guess is, people missed many things that were in the game that fell short in the movie.
I must agree, the directing and editing were "lacking", but the overall story (the screenplay) was superb. The voice acting was also top-notch.
If I were to go further into why I liked it, I'd have to explain myself with possible spoilers...plus I never saw or played the game, so I don't know if my assumptions would be correct. I'd have to know how the game played out and ended to compare the two.