Dorne has all kinds of problems. Ironically, Bronn pointed out how stupid this plan was before they even landed at Dorne. I wonder if the writers added that scene afterwards as a way of apologizing in advance for the mess they made with that plot arc. Of course Mycella is going to not want to leave. That leave 3 characters in Dorne: Doran, Tristane, and Mycella, that are not total idiots.
The scene with Stannis was excellent. It took me a while to warm up to him in the book, and it has been the same way with the show.
Sam didn't break his vow. Sam noted several seasons ago that the vow only forbids taking a wife, not carnal relations.
I had a similar response to Subba about the Sparrows initially, but I really like the plot arc now. Religious fanaticism is a frequent response to social upheaval, and the War of the Five Kings is definitely some upheaval. Fanatics will stand by their beliefs despite seemingly insurmountable odds, and I think the High Sparrow is proving to be a much better player than anyone expected. We are also seeing the effect of the power vacuum left by Tywin's death, and Jaime warned in the first scene of the first episode of this season.
I particularly liked the High Sparrow's smackdown of the QoT, which was not in the books but was excellent. She is finally appreciating how badly things have spiraled out of control. The retaliation against Cersei is simply punitive, she has two key assets sitting in cells, and has some tough decisions to make.
My problem with the Winterfell plotline is that an alliance with a bunch of stuck up lords like the Vale is impossible now with the way Ramsay is treating Sansa, and Roose would know that. The Bolton's are completely isolated, and have no chance of surviving short of some deus ex machina by the writers, and Roose would not have allowed that to happen.