About USER DATA. Ever see folk buy stuff on Amazon.com?
On a smart TV that's possible. Since the makers are downplaying this and we know the TV maker is not authoring the apps (I have a picture for you if need be) then you can never be sure the app is clean or has not been hijacked.
The TV makers do not answer basic security questions such as "What IP ports do I need to allow?"
Then we have Sony.