The Surface is a strange one, seeing as it is both a PC and a mobile device in one. There are upsides - as you've mentioned - but downsides too. I suspect my parents might not be quite as comfortable using a Surface than they are with an iPad. I'm glad your wife is enjoying it, though.
However, I'm really not trying to get into a war between platforms. My point is that adding limitations, which many of us see as reducing how powerful a device is, can actually enable the user to go further and do more than they could previously.