What you can do with it is broadcast videos directly from your device, you can do that publicly or to a selected audience of people who follow you, imagine skype meets social networking.
Video and audio are of good quality and as you record you can see how many users are watching you and who they are. You can share your video through Twitter and, if you wait a little after you've finished recording, the video will upload to the app and your followers you will be able to watch it for the following 24 hours.
As a viewer you can sign up for notifications that will alert you when one of your contacts is broadcasting and while you view them live you can send a text. Broadcasters can read your messages on their screen and answer you on video. You can tap the screen for "like"s, they appear as little floaty coloured heats ( meh).
I have been browsing the app in these past days and I must say that it's full of people just sitting on a sofa and asking viewers for questions. Silly stuff. Very silly. And of course the app is bound to be misused, after all there's a good percentage of porn in the web, but one can easily stay clear of that. I have watched reporters walking around the Expo in Milan, a potter being interviewed, images from a concert etc., interesting stuff.
Current state of affairs of self portrait, still on the easel
I set up my phone with one of those little bendy tripod on an easel between me and the canvas so it showed a close up of the surface. On the first broadcast I specified I could not take questions at the start but then later on I did look at the screen and had a few exchanges, though it was a bit distracting.
Set up for recording