No way to control the apps without an iPhone or IPad...which is what AirPlay does. I really don't see the point here. Improve the AirPlay to full HD seems more useful than trying to put apps solely on the ATV. They would also need to put more storage back on the ATV, don't see this happening with the current hardware.
Having to control the apps with a touchscreen to begin with makes this more of a fun hack than an actual useful feature. What's the point of displaying apps on a TV when I need to stare at the controller because of lack of tactile feedback ?
This is good for things which don't require much user interaction, like music/sound/video streaming applications, but for games and such...