He's still writing it and he's a slow writer so expect maybe 2014/2015.

is it any good?

I've been hearing a lot of good things about the Prince of Nothing series. Ever read that?

I haven't read it either. In the midst of purchasing the first book.
http://en.m.wikipedia.org/wiki/Prince_of_Nothing

Holy cow... you're actually doing it. I actually bought most of the WoT books at last year's BBW but the thought of having close to a year of my life dedicated to one series puts me off.

To be fair to George, he isn't new-age fantasy but he was a breath of fresh air to the genre. The popularity of aSoIaF has reinvigorated the fantasy genre. However, his books aren't traditional fantasy and attracts a wider audience than just fantasy fans. I wouldn't say the series has been "hyped to kingdom come" because that would insinuate that the series doesn't deserve the hype. It truly does. Not since Tolkien has there been a figure in the fantasy genre so universally admired.

Having said that, Lynch, Rothfuss, Abercrombie and Sanderson are the new-breed of "stars" in our genre. And they all bring something different to the table. Sanderson is by far the most prolific and his world building skills are second to none - but he also writes more traditional fantasy than the rest (hence why he was chosen to complete WoT).

Rothfuss, Lynch and Abercombie (especially Abercrombie) have gone down a different path and torn the script up a bit. No longer is fantasy black and white, the magic systems are no longer the main focus and the stories are far more gritty. Because of the pace of his writing, I believe Rothfuss will spend the vast majority of his career on the Kingkiller series. I believe Lynch has a good writing pace and if he can get over his health issues, we might see him do some great things. The Gentleman ******* series though, is pretty long and it may turn into a career long project rather than a career-making project. Abercrombie seems the most likely to be the breakout artist. He writes at a ridiculous pace (almost the same speed as Sanderson) and like Sanderson, he also is capable of writing different genres. He may not have Sanderson's world building skills but what Abercrombie lacks in world building he makes up for in character building. He's so good at it, George RR Martin considers him the heir to his throne. And he has done immensely well to keep the First Law trilogy short and made the rest of the books standalone.

You are correct. GRRM has said even said so himself with his famous gardener vs architect line.

“I think there are two types of writers, the architects and the gardeners. The architects plan everything ahead of time, like an architect building a house. They know how many rooms are going to be in the house, what kind of roof they're going to have, where the wires are going to run, what kind of plumbing there's going to be. They have the whole thing designed and blueprinted out before they even nail the first board up. The gardeners dig a hole, drop in a seed and water it. They kind of know what seed it is, they know if planted a fantasy seed or mystery seed or whatever. But as the plant comes up and they water it, they don't know how many branches it's going to have, they find out as it grows. And I'm much more a gardener than an architect.” - GRRM

Having said that, I don't think aSoIaF will turn out like WoT for two reasons:

1. GRRM has also "completed" the story in his head. He has said so himself. He already knows the fate of all the characters. What holds him up is actually tying everything together and to bring closure to the many minor plots.

2. This is probably the more important; the HBO show. There no deal in place that states that forces HBO to wait for the books. The execs already know how the story ends so they may actually overtake him which is something GRRM is very worried about. GRRM has not promised a certain number of books but he is trying his level best to finish it with the next two books because he knows he's running out of time.

Personally, I think we'll see 3 more books - The Winds of Winter (which is about halfway done) and A Dream of Spring which I think will be divided into a Part I and Part II (with a massive fight scene in each book dealing with both major "wars"). But I don't think any of the books will be "slow" books.

You have to understand that book 4 and 5 were very difficult books to write for George because he had to tear up his script. The plan was to fast-forward 5 years into the future but only after writing hundreds of pages of text did he realize it didn't work. So the 4th and 5th books has a lot of character building (as opposed to the fast paced all-action nature of book 3). While many fans found it "slow", it's integral to the story so we understand the characters' evolution better heading into the climax of the series. He had to cover the character growth of so many major players that he needed TWO BOOKS within the same timeline.