A Dance with Dragons is the fifth book of the series. I reviewed the last two here and here. The last one was a bit slow and this one was a bit slower, but I still enjoyed it and can't wait for the next book.
I've read some pretty hilarious and spot-on criticisms of this book, mostly that nothing happens. While this book doesn't need to be as long as it is (there are some excruciatingly elaborate descriptions of traveling through grass, snow, and river), there is a lot happening here. A new villain emerges (so much worse than Joffrey), Cercei must deal with her imprisonment, and new sides in the battle gather strength.
Some of the chapters read like filler, but it could be reasonably called character development. Martin is setting the stage here, moving the cyvasse pieces around the board, and getting us ready for the next installment.
HBO will begin airing the next season at the beginning of 2014.