It's been over five years since I read AFfC, so I won't speak on that other than to say my general recollection of it is that it's well written, if dull. The craft is sharp at least.
ADwD... is not a very good book. There's simply no other way to put it. I enjoyed Tyrion's earlier chapters, and I enjoyed the Ser Barrristan viewpoint chapter later in the book when he totally pwns Hizdar's bodyguard. Some of the Arya stuff is alright, too.
Pretty much all of the Jon, Dany, Stannis, Winterfell, Dorne stuff is just awful. As in, poorly conceived, plotted, paced, and written. Some of the King's Landing stuff at the very end is cool, I won't spoil it for those that haven't read it.
A case can be made that AFfC is a very well written but uninteresting book, unless boring minutiae is your cup of tea. ADwD is unquestionably a bad book. You're a stanley if you claim otherwise.