I kind of agree with Jaq on some points. What happened to Jeyne Poole in the books was beyond horrible, but she served as a secondary character and as a
catalyst for Theon to reawake his personality. Theon was the center of the storyline in the book, along with the whole unstable political situation in the North.
The show placed Sansa in Jeyne's place. As the writers said themselves after S4, Sansa was on her way from pawn to player and her character was actually growing after a few seasons of constant misery. Then this rape scene comes in. I think some people can say that Sansa will start her "avenge your siblings and yourself" actions after that, and that will push her to become a player in GoT further. Somehow I really doubt that's how it works for people who have been raped, but I don't have a lot of experience in this field, so alright.
The second problem of this character switch is how there is now another lead character and protagonist (Sansa) in Winterfell along with Theon. I've seen some people over the web saying this scene was more about Theon and not Sansa. The fact this conclusion can be drawn is, in my opinion, the problem. One of the main protagonists is being raped, and the scene is more about Theon. No way for me. The thithing is, this scene takes away from both Theon and Sansa storylines, taking attention away from the former, and basically ruining the latter.
See, I'm not saying this was unexpected at all, rather predictable actually. I was expecting this moment when the wedding had been announced, and yeah, here we are. Ned's death and Red Wedding were unexpected, yet predictable in retrospect. This rape is where it all was heading from third episode, so no big surprise here. Besides, why Sansa even had to leave the Vale? She was safe there. The Vale has an army unscattered by war. To avenge her siblings? Well, if Stannis has larger army and more chances to win, why don't go straight to Stannis? Or stay in the Vale and see the outcome of the battle. I'm not even saying that she is wanted by the Crown for helping to murder the king. Instead, she openly travels to Winterfell to marry the bastard son of a man who betrayed her brother stabbing him through the heart. "Avenge them" indeed.
Another point is I don't see the reason why Boltons needed Sansa at all. In the books they needed to arrange a marriage with a Stark because of their unsteady hold on the North, to be more legitimate in the eyes of other numerous Northern lords - they were invited to the wedding and all that. For these six episodes, I saw no Northern lords in WF at all. None on the wedding too. Ramsay seems perfectly alright with killing Lord Cerwyn for not paying taxes in episode two, so it doesn't seem like there are any problems on that front. Besides, if the wedding wasn't even witnessed by anyone, how Boltons can prove it even took place?
Eddard's death and RW were reasonable regarding the plot. This season storyline in WF for me is illogical. It seems like Sansa if there just to fill the quota of "awful things happening to the characters we love". It will probably move plot forward, but I expect it creating even more plotholes. If Sansa suddenly recovers and becomes a smart vengeful player or something like that, I won't find it very plausible. Maybe they will find some believable way to unfold the events further, but my faith in D&D regarding Northern arc and Sansa storyline is dwindling with each episode, and it's at its lowest point now.
I was holding my doubts in case there magically would be no rape, but now that there's no doubts, it feels good to post this rant here.