Intuitive to Nokia users, but I don’t think folks coming from other platforms have picked it up. If you press and hold the home key you get a list of recent apps, which makes switching around a lot easier if you’re bouncing back and forth. Here’s what the app list looks like when it comes up:

When you tap the widget once it brings up a selector with launchers for each of the apps you’ve added plus an icon to start the widget configuration interface. Here’s what mine looks like after tapping on the widget:
And what the configuration interface looks like if you tap on that center icon:
I think it’s a pretty slick widget. Great way to increase launcher density if you have a few widgets taking up some space. And it looks pretty good there on the home screen.