I got my Shield TV so I could stream games from my pc to the big screen and audio system. You can install apps onto it, like pandora, spotify, netflix, etc.

It has since become my go to hub when not watching something on cable. I just recently reripped my cd collection into FLAC and stored it on my shield for playback.
I still need to learn more about what I can do with it, I know there is a lot of functionality I'm not using. For example, it has plex built in, which I hear is an awesome thing...