Just watched the episode. Still trying to process that scene, but for now, I'll say two things: as much as I hate what happened, the scene itself was wonderfully directed and acted (top marks to Dillane, who actually made me feel something more than just outright disgust and loathing towards Satannis), and Shireen's screams are going to stay with me for a while.
As for the rest of the episode? Meh. God Mode Ramsay and his 20 Good Men somehow manage to sneak past an entire army and burn the apparently unguarded supply tents without suffering a single casualty? Next episode, I'm actually half-expecting him to do a shirtless kamikaze charge into Stannis's forces and STILL come out unscathed. Arya's scenes should be exciting and intriguing but just seem to drag, and I'm not sure the Meryn Trant, Pedo of the Kingsguard reveal was necessary. Guess we couldn't have an episode without at least an implied rape. Nothing happened at the Wall, and by this point I'm sure even the densest of the unsullied are expecting the "shocking" twist in the next episode (but hey, let's have Olly glare at Jon for the 150th time, just in case we haven't telegraphed his betrayal sufficiently). Dorne continues to be an utter waste of money, acting talent and screen time (seriously, we lost Jaime's Riverlands story, Lady Stoneheart and other book material for this?). Brienne is MIA once again, and presumably still hanging out outside Winterfell (it's hard to believe they cut her much-reviled AFFC material and STILL managed to make her arc this season even more boring). Daznak's Pit was horribly staged and lacked any kind of tension (there was one awful prolonged moment when the harpies were surrounding Dany and her entourage but nobody was actually doing anything, like they were all waiting for a cue from the director. It seemed to go on forever). I did think the dragon-riding CGI was absolutely fine, however, especially for a TV show.
Man, reading that back, I sound like a complete stereotype of a disgruntled book reader, but believe it or not, I used to defend the show to the hilt when people would complain about D&D's changes or the declining overall quality. It's becoming increasingly harder for me to do so.