I believe it's the "TV" part of Apple TV that throws people off. It won't be a TV. It will be something that moves beyond what has come before. Many of the purported Apple TV features can be found in multiple products, executed multiple ways throughout multiple industries. But Apple's genius is how it puts them all together, introduce some new ones and brings forth a new paradigm. It will completely alter what people think of a TV.
Go back and look at the Keynote that introduces the first iPhone. We take for granted that all smartphones work in similar ways now. But when Apple introduced their complete re-think of what a phone should be able to do and how it would look while doing it, it was groundbreaking.
I think most get hung up on the hardware / software technology side of things. But if you start from the premise of use-cases and lifestyle, throw out all the current rules, then you get to a completely different place. A place Apple has brought other industries before, ie. computer, music, phone and tablet.
Think of it this way: Apple always starts from the "Idea" first, then attacks the tactical execution by which to bring it to life. They didn't invent iTunes first. They said, "We love music. We want it to be easy to legally purchase songs digitally and cary 1000s of them around." That was the idea. ipod and itunes was how they brought that idea to life.
So the real question is, what is their "idea" of what a TV should be able to do and what will it look like while doing it? Judging from past experience, I look forward to how they decide to answer that question.