I'm only 30% into Fire so these are definitely preliminary comments.
I really enjoyed Graceling. It had an inventive world, interesting characters and after the longish introduction a good adventure. I was really looking forward to get back there with Fire. But instead of the same world with different characters and adventure I've stumbled into what seems like an alternate reality - a different world with the same characters and adventure. Other than the historical placement and the presence of "powers" this world is unrecognizable and as far as characters go, so far it just seems that the author took the personalities of the original characters, stuck them in a blender and blitzed them to create these "new" ones.
So far this is barely 3 stars for me, more like 2.5. I still love the writing style, even with almost nothing happening I keep turning pages with gusto!