As promised, now that I've finished all published volumes in George R R Martin's "A Song of Ice and Fire" sequence, here's some thoughts about that, and about other GRRM topics.
A Song of Ice and Fire
So, firstly, the Obligatory Topic when discussing GRRMs work: Protagonist Death.
(I am told by Wikipedia that a Protagonist who doesn't last the entire work is actually a "false protagonist", but this seems to require retroactive continuity when talking about a work in progress-if a protagonist dies in Book 4, does that mean that they were also a false protagonist in Books 1-3?)
GRRM claims that he's always felt that protagonists (and, viewpoint characters in general) shouldn't be invulnerable just because they're a focus of the reader's attention. Indeed, he holds, the only way to really get people concerned for the protagonists is to kill some of them off, thus making any subsequent peril implicitly more threatening to the remainder.
Unfortunately, I do wonder if GRRM is taking this a little too far with A Song of Ice and Fire. While each book contains relatively few protagonist deaths, GRRM seems to have a talent for mostly killing off viewpoints that the average reader sympathises with. (Not so in my case - I am betting on Tyrion Lannister surviving to the very end†.) Presumably, there is a significant fraction of his readership who currently don't have any viewpoint characters left who they empathise with.
This is exacerbated, of course, by the construction of the current "last" book, which only follows about half of the surviving viewpoint characters (the remainder due in the next book), but that isn't quite the same problem (even if it has a similar effect).
One interesting strand which GRRM seems to be weaving into A Song of Ice and Fire is the process of reinvention of the self. Most obviously, by the end of A Feast for Crows, both of the Stark girls are well progressed in the matter of their reinvention - although, Arya ultimately rejects her reinvention, while Sansa seems to be submerging herself more deeply. One might extend this to the more traumatic reinvention of their mother, as a result of her resurrection (of course, the nature of Catelyn Stark's resurrection, coupled with the matter and context of her death, seems to have resulted in her "new" personality being considerably more vengeful than it was before. Presumably, if she ever discovers that some of her children are still alive, she's going to suffer a psychotic break or something (which does, of course, make us wonder if the last word Brienne shouted was "Arya"...)).
One element which I believe may slightly annoy me if it develops in the way I suspect, is the hinted at conflict between intellectual study and magic. Dragons (in one of the more predictable tropes of the books) are apparently a wellspring for magic, presumably through one of the two mixed metaphors for the Fire/Ice dichotomy*; when Daenerys hatches her eggs, magic begins to become more powerful across the world. Apparently, the Maesters, who represent scholarly learning, killed off the last lot of Dragons in order to remove magic (==sense of wonder?) from the world. I do hope that GRRM's resolution of this isn't a variant on the trite "magic is unrational, and hence rational study must oppose it", since then I'd have to mock him mercilessly (and, of course, I'd be bitterly disappointed by such a lacklustre development).
†That said, I am a little grumpy that Oberyn Martell was killed off in the same book he was introduced in. He deserved a lot more screen time than he got-and even his Daughters seem to have been neutralised before they could be equally awesome. And, it looks like even his felling of Gregor Clegane was for naught-the inevitably disappointing unveiling of Qyburn's Frankensteinian creation seems to owe much to the existence of Clegane's body in a not-quite-dead state...
*GRRM seems to be interchangably using two metaphors for the central Ice/Fire dichotomy. In one, Fire apparently represents Magic, and possibly the Creative and Vivacious impulse (this appears to be predominantly so when in the context of Dragons). Ice, therefore, represents Order, but also the Rationalisation of the World.
In the other, which we are explictly told later on in the books, Fire is "that which consumes" and Ice "that which preserves". Hence, presumably, the way in which the more potent magical abilities of Fire Priests seem to use up some of the soul or life-force of their recipient, and also the icily preserved nature of the undead Wights used as foot-troops by the Others.
Of course, these metaphors are apparently in contradiction - the magic used by the Others is apparently within the Ice metaphor, which contradicts the Draconic metaphor entirely (note, however, that dragonglass and magical items like Valaryan Steel are apparently deadly to Others). Additionally, it seems that Wights aren't simply preserved - they appear to be given new life of a form, although of a particularly focussed and non-sentient nature. We might argue, therefore, that the key role of the Ice/Fire distinction is in the murky area of the Soul; this, of course, causes deeper issues with the nature of the Others themselves (who, being the only truly non-human sapients in the setting, we are forced to treat as unknowable - freeing GRRM to use them as Bad Guys, as they're the only people he doesn't humanise. You might argue that this is a bit of a cheap trick,a and you might be right. On the other hand, it's also a trope of the Fantasy genre - for which, see below...)
Furniture Rules
Except that, at all but the highest possible level of abstraction, it really doesn't.
To explain: GRRM has a famous theory that, at least in "genre" fiction, the differences between SF and Fantasy and Horror (and Westerns and ...) come down to "furniture". The story is the same, but the dressing up is different.
It seems to me, to extend the metaphor a bit, that this is overly dismissive of furniture, for a start. A great big oak table takes up a lot more space than a tiny formica one; not only does this affect what you can use them for, it also affects how easy it is for you to move around the rest of the room. In the context of writing, there are some stories that you simply can't tell in a given genre (for example, it should be impossible to tell some High Fantasy stories in a Hard SF setting) - the furniture gets in the way, or it falls to pieces under the weight of the dishes you're serving. So, Furniture Matters.
But, more than that, there's a deeper difference between genres than the furniture analogy suggests.
For example, as I've mentioned before, Star Wars is very obviously Fantasy with SF furniture. (One of the mistakes the prequels made was to try to extend the furniture into the background structure, leading to the obviously-wrong concept of midichlorians.) If furniture is all that matters, how is it that I'm able to make that judgement? Indeed, the furniture rules theory doesn't explain other examples of this kind of genre-mismatch either. (I suspect that GRRM considers Star Wars to be Soft SF or something, though...)
Similarly, taking GRRM's own work - A Song of Ice and Fire is very obviously Fantasy, in ways which are intrinsic to the story (threats from the Distant Past when Magic was Stronger, the symbolic connections between Dragons and magic etc) - it is not clear how you could write it as, for example, a Western, without modifying the plot and story itself. Westerns just don't have threats from the Past, or work on the same kind of epic scale (usually), and gunslinging is entirely different from close combat with swords (or sieging castles, for that matter).