The thing I appreciated most about the fic was the originality. You dared to do something different.
I personally feel you did a good job and set a new level of quality for your writing. But i believe that you are merely scrathing the tip of your potential. You have potential to become better still.
One thing you need to still work on is description. And by that i also mean describing things pleasantly so that it leaves a vivid sketch in the readers mind.
I thought that this fic was a bit rushed... i would have liked to see more into the Harry-Katie relationship. Till the end I couldn't figure out if they had made the transition from friends to lovers. I also would have liked to find out why Harry felt he had to commit suicide.
The power of love is a life giving force... it does not allow any thoughts of suicide.. so I was disappointed at that angle.