A Dance with Dragons: Dreams and Dust
Runs concurrently with book 4, following the people who were missed from that book.Fortunately, this means we're spared the ravings and whining of House Stark's remnants (apart from Bran and Jon Snow, who get more than their fair share of pages).
This book seems to be less bloody than some of the others, it's more to do with moving pieces into place. It's good enough, and helps fill in gaps, but could have had less pages and achieved the same result (and presumably book 5 wouldn't have had to be split into two parts).
