It's a very fast 6 hours.
The story is "good," but a little shaky in some parts.
Graphics are decent and the controls are quite good but not the best. I actually adjusted the video settings and my TV brightness as all the "white" was just too much for me.
Sound production is top notch. The enemy AI is decent, but the disarm moves are a bit limiting. I don't think they intended this to be much of a combat game and this will displease many people.
I would recommend you rent it first as the main story is no longer than 6 hours, and if you enjoy it that much then please buy it and enjoy the time trial modes.
Replaying through the chapters and unlocking all the time trial modes will add about another 3-4 hours to your experience, but improving your time trial runs is (of course) all about moving through the best routes as quickly as possible while using Faith's moves as best you can.
Personally, I can't say I feel motivated to play through the story again, but I do enjoy the time trial mode. I wish Dice had implemented a "free roaming" mode just for fun, but I'm probably one of the few people who would request such a thing.