They are pretty common from what I've been noticing.
I think a lot of it is people replacing older PCs with new Mac laptops, picking up the AppleTV because it is so cheap then finally buying an iPad as more of a curiosity.
A lot of them didn't really pay much attention to the competition because they weren't serious, considered choices.
if you've heavily invested in Apple media, the benefits to an Apple device would probably outweigh any individual feature wins of the Nexus 7.
if you're more of a casual Apple household, meaning just hardware and no media, the Nexus 7 is likely a fine choice.