I've ridden my friend's 500R. It felt just like the 250, but a little heavier and with a little more power. Definitely still capable in the twisties, but a little less high strung at highway speeds than the 250.
It's a nice bike for doing whatever you want it to do, just like the 250
Other than that, I couldn't find any real glaring issues from the 30 minutes of riding it.