Haven't finished Feast for Crows yet, but here's a few:

1) The worst sex scenes in the history of everything (in a published work). Sometimes I have to wonder whether George is actually a 13 year old in a fat suit.

2) Some truely awful sentence-by-sentence writing. Improves drastically over the 2nd and 3rd books but jesus christ George breaks the 'Show, Don't Tell' rule so often he now owes it a military funeral and a widow's pension.

3) Esteros sections are not as interesting as the Westeros ones. Not even close, and this is compounded by how (so far) they're almost vestigal to the main story. Maybe I just prefer low fantasy to high, but there you go.