Mr. Martin wrote three of the most amazing fantasy novels ever created between 1996 and 2000. Over the past 11 years he's released exactly one half-a-novel (missing the main key perspectives in the story) that does nothing to move the plot lines forward from the conclusion of the 3rd installment, and leaves the main characters hanging in limbo. Just look at the reviews for installment 4: A Feast for Crows.
As such, many of George's early readers from the late 90's and early '00's have been waiting 11 years for the next Jon, Tyrion, or Dany chapter who are the main characters central to the story.
New Readers beware: Martin no longer makes a concerted effort to finish this story, and only writes on it when he feels like it. He's moved on to other projects, namely his Wild Cards series, HBO show promotion, and numerous fantasy anthologies. He attends approximately 6 sci-fi/fantasy conventions and takes approximately 60 vacation days per year. Just look at his Not-a-blog to see what he truly values.
He's extremely dishonest with new readers and current fans by telling anyone that will listen that the series is his #1 priority, and that he's worked supposed '12 hour days' on the series over the past decade, which is laughable.
He publicly berates his fans for being impatient, declares that he owes them nothing, and has announced that 'You see, you cant please everyone, so you've got to please yourself.' when discussing his lack of progress on the series over the past decade when taken into context with his other projects.
He's made it very clear that that he's much more interested in his side projects, than the story that made him famous. For the upcoming book, A Dance with Dragons, he's broken numerous deadlines since 2000, and in January 2008 informed his readership that deadlines on the project were beneath him, and that it would be completed 'soon'.
Even after A Dance with Dragons, there are two more novels to be written to bring the Song of Ice and Fire to a conclusion, and considering that GRRM's attitude and the fact that he's 62 and grossly overweight, there are no guarantees that he'll ever be done with the series.
So buyer beware, understand that if you purchase book 1 that GRRM owes you nothing, does not make an concentrated effort to finish this story, and will probably die before this series is completed. If you value your money, and detest unfinished epics, I'd suggest picking this up from the library.