My big problem with the game was the engine more preciesily the movement and physics of it.
It felt so clucky as if you where stuck in the Big Daddy suit. You could chuck grenades about 3 meters and the walking speed was painful. I found the whole experience almost claustrophobic. This may be a biproduct of realistic gameplay/physics, it was improved in q4 but still there.
With all that said, it had some amazingly good points, the lighing effects being one of them, it really did have some scarey moments, something few games achieve. I completed the game, but would struggle to do it all over again.