I've been pushing for this kind of in-between device for ages. I always thought Nintendo would do it, with their whole "Wii Channel" interface, make gaming on the same level as television, accessible through one interface. No more "turn on and switch inputs to gaming," rather fully integrated and no longer a second-class citizen. Clearly they went a different direction with the Wu, instead making them equals by providing a second screen you can use while watching TV. It's neat to see that one of the other major players is going the other way, though.
Still can't imagine GETTING one, since the PS4 will have exclusives I want and I really don't want to own two machines that are identical bar a few exclusives on either end, but neat nonetheless. Maybe if they sell me a super-cheap one later on I'd get it just for the TV functionality.