Not yet. To be honest, I don't think it was that the fourth book was that bad, I think the third was just that good. I remember being kind of let down by the fifth as well.
Everyone knows the show is going to catch up at this point. GRRM still kind of denies it, but he's pretty much not capable of finishing both books before the show winds up. His latest statment is something like:
I'm now worried about it catching up, but if they split the next two books into two seasons each I might be able to do it - especially since they have to alter the format from the books as the following two aren't in chronological order. The last one will still be very tight though.
Of course that's a really shit idea, especially if you've read the last two books. There's already almost not enough there to make two full seasons all that compelling for television.
The show creators (I may have made this up) have said something like:
We've been briefed on a rough summary and timeline of the overall plot of the series. We can progress beyond the books if it comes to it
I think the second option is what's going to happen. Of course that's problematic, because I'm sure the publishers will shit a brick if that happens - it will probably cut their sales in half...at least. My guess (and I think this is a cool idea that I made up, but I'm sure it's a thing out there) is that they pick a point and diverge into two different timelines, showing how one event can change everything for Westeros - I think it'd be a decent way to keep the casual fans interested in both the TV show and the books. My guess for the divergent point would be
John Snow's fate at the end of book 5 - although I think the Red Wedding would have been a better point, but we're too far past that.
In either case, I think it's too close at this point for them to not have a contingency plan that the publishers and the producers are both somewhat satisfied with. No one has faith in GRRM (nor should they)
