Here're some brief thoughts on the first episode of Season 6:
First the bad.
I thought the direction during several scenes was less spectacular than what we've become accustomed to when watching Game of Thrones. Though the Castle Black stuff was exceptionally well composed, blocked, and cut, the Sansa/Theon scenes, the Tyrion/Varys scenes, and the Daenerys/Dothraki scene were off. Even the Arya scene was not well shot. The worst shot scene was clearly the sword fight (Brienne of Tarth) in the forest. It was inexcusably poorly executed. Did they not have a long enough production schedule to take the time to shoot this right?
The Tyrion/Varys scenes underwhelmed visually. These are supposed to be $10M episodes. There seemed to be about twenty extras in the whole village. It was too small.
Some of the actors looked different. They either aged or gained weight. It was noticeable in several scenes.
Now the good:
The Castle Black scenes were spectacular. Well written, acted, and shot. If John Snow somehow rises, they at least didn't blow that load too early.
Lena Headey did some phenomenal acting.
The special f/x of the ships burning in the harbor was good. If it had been at night, it would have looked more spectacular.
The last scene with the Red Woman twist was an intriguing reveal.
So far, though, this early on, the Showrunners have oversold this season. They claim it's the best one so far, without any weak episodes. After the first one, I'm a bit underwhelmed.