A bit bigger complaints for me.
I'm a big fan of the books, but I actually started watching the show before reading the books, so I've been back and forth. But I've found, as the show went on, that whenever the show started deviating from or going beyond the books, the plot lines and dialogue have suffered greatly for the most part. Once the show doesn't have GRRM's content to go from, they really seem to do a poor job of it IMO.
Dorne is the best example, but I'm really not that impressed with many others. I didn't think the opener was all that great, actually.