I thought the world building didn't make a lot of sense, personally, and I thought the first book cheated in how it got the main character out of the moral dilemma at the center of the plot, but the author is one of a handful of people who hit at just the right time and in just the right way to transcend normal book sales and move into the realm of Harry Potter, Game of Thrones, and Twilight. That's talent.
She was already quite successful before Hunger Games with her Gregor the Overlander series, but HG was next level stuff.