The feed will show a lot of things -- and it may turn out to be more than you'd like to share. I limit mine a bit because otherwise it's a lot of info going out there into the ether. You may feel differently but a lil mystery is kinda nice.
The main things I share are fitness minutes and when I've blogged. How many points I got on the wheel? Eh, not so much. But if you want to share that, go for it. :)