Huge parts of the game were brilliantly done. The writing, voice acting, motion capture are some of the best ever done in a video game. The environment and assets are incredible, the amount of music and soundwork and ambient dialogue is just insane.
They just crunched it too hard and pushed it out too soon. The foundation was there, but there were two many bugs and half baked systems that means that no matter how good the foundation was, the gameplay loop suffered, and immersion was killed.
It was never a bad game, it was a brilliant game made with love and passion, pushed out before it was done.