Where to begin... for starters, if you're writing a story and you write a sentence that's only two words long in the middle of a paragraph that's not spoken dialog, you're probably a bad writer.
Another thing, I'm fairly certain that the writer has A.D.D. You know how stories generally have a protagonist or a small group of protagonists that wont generally stray too far from one another because the story is based around them? Well, from what I can gather, A Game of Thrones has... about eight unless I miss my guess. Not only is there alot of people to keep track of, but at the present time in the story, they are currently divided into four very separate groups.
Further more, you know how usually in a movie someone will ask about something he and the audience doesn't know anything about and then another character will be all like, well, you see, Billy, it works like this... You know, the proper way to provide exposition? Well, in this book, one of the many main characters was on a boat, observing her destination that just came into view, and out of the blue we get some back story on the location itself and what it looked like hundreds of years previously. For no reason. Just because. It was also completely pointless and had nothing to do with anything going on at the time, and it had no framing device what so ever. Just a little history lesson mid story because, as I said, the writer probably has A.D.D.
And god are parts of it boring as hell. It doesn't help that a large portion of the protagonists are children, providing many memorable lines of text, such as when one little girl was complaining about how her sister was better at stitching than her, but at one point, and I'm not kidding here, for a couple pages, what I was reading in this book was what a character in the book was reading in the book he was reading! And, big surprise here, it was completely pointless! Oh sure, it was a LOT more interesting, mind you. About a war centuries past with dragons and ****. I found myself thinking, why the **** can't I be reading that book instead? And I mean the actual book, not through another character.
Oh yeah, here's something I found appalling. Early on, two of our main characters find out their is apparently some sort of conspiracy going on and the king's right hand man may have been killed by a rival noble family. Oooooo, suspense! Sounds like we have a who-done-it story on our hands... for all of the rest of that chapter because it's revealed in the very next chapter who did it. Gee, I was almost finding the story interesting.
I don't want to spoil too much should anyone feel like reading the book, out of some morbid curiosity I suppose, probably the most ******** thing I've read so far was... okay, this requires some explaining. After the prologue, which was sadly the most interesting part of the book so far, this dude finds some direwolf pups with a recently deceased direwolf mommy. Not only is this the first time anyone's seen a direwolf in that area for many years, but the symbol for this dude's standard is a direwolf, and their are exactly the perfect amount of puppies for each of his children, including the ******* son he has, and there's the perfect ratio of boy and girl puppies to boy and girl children, BUT each direwolf's personality mirrors the child they're given to perfectly. If that wasn't enough, the book goes into much detail about just how freakin' special and supernatural these wolves are. They're like these kids guardian angels.
And then, in a couple paragraphs much later, the book just casually kills one of wolves off. And for no real reason either. Not trying to save the life of one of the children, no, but because one of them attacked this one guy defending it's kid and while that one got away, it's sister was shanked because... it was there. And person who ordered it is a ****.
Well played, George R. R. Martin. Way to go out of your way to completely undermine all that effort you put into making those wolves seem awesome. I guess the one that died just wasn't special enough. What awful story telling, George.
tl;dr - Some much better writers are, but not limited too: J. K. Rowling, R. A. Salvatore, John Flanagan, and Garth Nix.
EDIT: I will say this. The characterization of the butt load of protagonists in this book is pretty good, but it may just be me feeling bad for them because they have to be apart of such a poorly written story.