Things you can do include locking and unlocking the car, setting it to heat up or cool down before you hop in, and viewing the status of the car. (No screenshot was available from Audi, so you're looking at the iPhone version of the app up top. Just imagine it larger and more horizontal.)
Who's it for? People who have the latest Apple TV, a new Audi, and would rather control the latter with the former on a big screen than a smartphone. In other words, we're not sure. We do wager that there's a decent amount of overlap between Audi drivers and tech early adopters, so someone will get excited by this. And since the new Apple TV is based on iOS, it probably wasn't too tough to port the iPhone version of the app over.
Like a lot of what we're seeing at CES this week, this is likely a small step in the direction of increasing connectivity between all of the digital stuff in our lives and our cars. We'll get more excited when the family flatscreen turns into a live window of what your car is looking at. But also terrified.