Is Windows 2012 Remote Desktop Session Host better than Citrix XenApp?

At Citrix Synergy in Barcelona, this was a very good question that a number of partners were reporting their customers were asking. Citrix XenApp 6.5 is a market leading product. Windows 2012 is very new. What are the differentiating features, what key questions should you ask and how do you decide on the one for you?