Well, actually, just to clear up some mistakes: One, there isn't any such character known as Aya in the actual movie, and two, the movie (i believe) is based off the novel and not the video game. The video game is more of some side story of sorts from the original story. It's good indeed.
Personally, I thought the movie was good. It's definitely not like the game, but it has a great storyline in itself with impressive visual effects. I think you should at least give it a chance.