I think Microsoft is loosing the tablet space and winning the desktop replacement space.
right now they are all grouped under tablets, people are in the process of converting from desktops to these new desktop replacement tablets and this is a huge growing share of the tablet space.
Not an Apple cheerleader, but I can spot trends in the market. Look for the new tablets from companies like ASUS and Nvidia to make huge headway as they work on gaming desktop replacement tablets.
The only real issue is IOS will never be a full OS and requires separate versions of apps.