While most people probably only became aware of George R. R. Martin's "A Song of Ice and Fire" sequence with the launch of the HBO TV adaptation, "A Game of Thrones" this year, fans of the original novel sequence have been waiting for 6 years for the most recent book, "A Dance With Dragons", not without some bitterness from some of them.
Now that it is finally here, how is it?
Well, it's basically everything you'd expect of Martin from the previous novels: a somewhat dark, mostly realistic medieval fantasy, which doesn't flinch from depicting the worst kind of people, as well as those who aspire to being the best. (Martin is not lacking in cynicism sufficiently to believe in perfect heroes, although he's happy for people to claim to be such.)
Of course, the grittiness of the setting suffers somewhat by comparison with more modern works that attempt the same thing: in the 15 years since the first book, "A Game of Thrones" was first published, writers have been inspired enough by its then refreshing grit, and tendency to kill off even apparently major characters, and now "A Dance With Dragons" is just another novel with such a setting.
Where Martin still excels, however, is in the complexity of his plotting and internal referencing; multiple long-running plot lines continue in not entirely expected ways (I don't think anyone who had read the previous books would quite predict Tyrion Lannister's story in this novel), and long-buried comments are referenced for the awake reader. (I must admit, while I was proud of spotting some of these, I missed others due to the 6 year gap between this book and my reading of the previous one, and even missed something that I suspect Martin expected to be obvious in the later sections in Winterfell...). Sometimes this gets a bit much, and while Martin has apparently tried to build in a few more hints for the reader in deference to that long inter-book stretch, it is quite possible for a reader to miss one thing while trying to remember just who that other guy was, or what that prophecy was about, precisely.
There is also some lovely use of the chapter titles; with so many viewpoint characters, Martin has traditionally named his chapters after the viewpoint character in each one. However, several characters with changing personal identities in "A Dance with Dragons" get chapters with variable names - the name of each reflecting their particular self-image in the chapter in question. In one case in particular, this underscores a particular case of self-rediscovery that would be awfully cruel to spoil for those who've not read the book yet.
Is it worth buying? On balance, yes; although, as with many multibook sequences, this kind of recommendation is moot; readers of the previous books will buy it anyway to find out what happens to their favorite characters (especially because some of them haven't been seen for a whole book, due to the way Martin split up plot between "A Dance With Dragons" and "A Feast For Crows"), and those who haven't read the rest of the series would be lost without doing so (or perhaps waiting for the first 4 seasons of the HBO TV series...).
The only consideration now is how long the final two novels will take to produce - with the TV series using a novel's plot per series, Martin can't afford to take 12 years to put out the two of them; if two novels even prove sufficient to complete the whole narrative (originally a trilogy, then a quartet, a sextet and now a septet, the amount of plot that apparently remains still seems too big for only two novels to complete).