I thought the incident was handled tastefully for that sort of thing. It isn't the sort of thing I care to watch, so I'm glad it happened off-screen. But it did feel like the natural progression of the story and it made me intrigued to see what happens next. And it very clearly communicated that Sansa's current situation is a lot more dangerous than any she has been before (which is saying something). It also established that Ramsey is even more despicable than Joffrey was.
Yeah - I'm kind of surprised there's a backlash against this scene more than there was against Jaime raping Cersei last season, which IMO was much worse on many levels (change from the book, definitely nonsensual as she resisted, more explicit, not justified by ongoing story/character context, etc).
I can't help feeling that the campaign of "GoT is waging a War On Women" is a result of die-hard book fans wanting to scoop up easy support for a go at the TV show that's taken a change.