So I see they updated this recently where now during sports it asks you what your predictions are for the next plays, or who do you think will score next, or if this drive will result in a touch down, punt, field goal, or other. Every right answer gives you points, and you are shown your average percent correct compared to everyone else playing. It's an ingeniously fun way to watch sports.
My only issues was a couple times it didn't update fast enough to see the question before it timed out (you get 10 seconds to answer). Also if you are in one of the play highlights making a comment or drawing a picture, you won't know there is a question being asked either. Otherwise you don't have to pay attention to the Wii U screen because it will beep when a question has been asked.
I generally don't watch a lot of sports, but the update made it a lot of fun to do so. There was quite a few people using TVii as well, so it was always fun to see everyone's comments/drawings, which are generally a lot nicer than you'll find elsewhere on the interwebs. I can't wait to use it for the Super Bowl, and I might actually watch a pro bowl game for once just to use TVii.
As a sidenote, why does TVii have colored drawings, but Miiverse doesn't?! Come on Nintendo!