Characters wandering about the landscape, sometimes in circles. Plotlines unresolved while new characters are created and new plotlines set off. In one of them (can't remember which one now) it ends with a strange postscript explaining that the reason that so many previously important characters did not figure is because he could not find space for them in this vast tome, er, sorry about that. I have never seen anything like that in a book series. So why keep creating unnecessary new characters? It looks to me like the series had at one point a cataclysmic ending in view - Ice and Fire, the White Walkers coming down from the North and the dragons coming from the East, no doubt to meet in some Westeros Ragnarok. The trouble is that that doesn't fit well with the idea of a Wars of the Roses type feuding families and shifting alliances and that he got more interested in that.
If you're into stuff like this, you can read the full review.