I used to live there - I left a while ago, so my info is not all that current.

I never felt in any danger whatsoever, far from it. I found the local people to be friendly and welcoming, and the mix of cultures fascinating. I didn't see or experience any major issues in my time there (employers notwithstanding). Xinjiang is absolutely beautiful once you get out of Urumqi, which is a bit of hole. Whatever you do, don't believe the negative propaganda you'll read about Uyghur people. It's bullshit. They're lovely.

That said, there were major riots in 2009 and a few issues last year in the southern areas, and I can't imagine they would have been especially pleasant to get caught in the middle of. Nobody can guarantee that these problems won't be repeated, so that's something you'll need to consider. The machine-gun-toting, ten-man, Han-ethnicity riot squads constantly patrolling the 'ethnic' neighborhoods are a sight to behold!  

Should you go? Well, that's up to you and how adventurous you are. But I really, sorely regret not getting to spend more time travelling around Xinjiang.

If I can help at all with more info, then inbox me

I imagine it's only dangerous for Han chinese. If some people were shipped to your home country by a crazed dictator and pushed your people off of their land and eventually tried to push their alien culture and traditions on you while punishing you for speaking your language, worshipping your God and other things then I imagine you might be a little perturbed too.