Exactly.

He's got a bit the Dumas/feuilletoniste syndrome. Not that their styles compare, but Dumas wrote with a bit the 19th century equivalent of Brandon's prose: good schoolboy language, written too fast to be polished or truly interesting, and not enough revisions (in Dumas's case it was none at all - and no editing, but that doesn't work anymore these days). Characters have similar flaws too. From time to time they'll come up with some really good ones, but a lot of time they're fairly generic, or relying too much on a few fun flashes, or are way to single-purposeful. But the flair for fun story is there, the storytelling craftmanship is developping over the years.

I've nothing against entertainment literature, but when even a non native speaker can spot semantic or grammatical mistakes, that gets in the way of good entertainment.

Martin's problem in ADWD, IMO, remains that he didn't have a good story to tell about those events covered. When his plans for an ellipse didn't work he plowed to come up with something, but it's laborious, somewhat overwritten, with an obvious lack of enthusiasm.