I find it interesting that a "killer feature" is talking to my TV. I find the Apple remote quite easy to use within Netflix for scrolling etc. and don't really have a problem using my iPad as a remote if I want to type things.
Perhaps I am just old but voice recognition is a great feature, but not one that would "kill" the competition or make me chuck my AppleTV 3rd. gen in the bin to rush out and buy an Amazon device.
I would therefore not label it "killer".