"The ultimate problem was that the first few books imply that the overall story would be about a boy growing up to be a hero, and what we ultimately got was the story about a patsy who was manipulated into fulfilling someone else's overly complicated scheme to preserve the status quo of a society that didn't deserve salvation."
I wholeheartedly agree with that.
The Deathly Hallows = Deux ex machina (literary device) + Hermione's knowledge + Sheer dumb luck
No matter who you are, if you are writing HP ff you should never mess with:
Gamp's Laws of Elemental Transfiguration
I think that is pretty much everything.