"During those years the unsocialized were snarling at Martin for being lazy or procrastinating or indolent or whatever, he wrote about as many words for novels as I had. By this superficial but easy-to-quantify metric, on the novel front he was as productive as I was, and most people seem to agree that I’ve been pretty productive these last six years. I just spread my words around five novels while he poured all of his into one."
I'll admit, I was one of those people who bitched about Martin taking six years to write a book, and Scalzi's analysis proves that I was wrong.
I think the main complaint is that the books are so good that's a bit of a letdown when you get to the end and there's so much story left to tell. The last book is no exception.
The chapters jump around between the different characters, and at the end of every chapter you're a little annoyed at reading about a different character. However, halfway through that chapter you're so engrossed in the character that by the end you get annoyed when it switches back or switches to another. And yet, I loved every minute of it.
Get the book. Read it. Seriously.
(Full disclosure: buy it from the link above and I get a few cents. Yay me.)