Not sure about outside the U.S. but at least here:
Setting up TVii with your local TV, local cable provider, netflix, or other video on demand services lets you access a super guide for programming. It can change channels or load VOD through the interface.
For sports, it's fun if you watch sports by yourself. Many of the plays during a game get "tagged" and are displayed on a feed. If you are viewing the feed for a game, you'll see them appear on the gamepad. they have screenshots and you can doodle on them. you can also post text comments and converse with others or simply just emote happiness or sadness, etc... did I mention that they post screenshots from matches and you can doodle on them and post them?
You can pull up a TV guide on the gamepad (more useful than it sounds) and switch cable inputs to the channel you want. You can favorite shows, and it also lets you browse by themes or related shows. If you pick your favorites or select any show, it will automatically pull up a list of ways to watch it, (cable tv, netflix, amazon) and tell you when. It works best if you have a few services connected (I just have cable TV).
Even with the TV shows, the more popular shows get "tagged." So if you are watching their feed, they display screenshots with captions from the show, you can doodle or post text comments.
It's a useful service if you watch a lot of TV. I personally find it more useful for football (and there is much more interaction with users than for regular TV). The interface is clunky and slow, but the gamepad does pretty much everything Kinect 2 does for the TV during their XB1 demo, as far as I can tell.