Jetpack - great plugin. I didn't notice how much I had been relying on it until it broke.
I only noticed about 48 hours later that Jetpack had spontaneously uninstalled itself. This meant no stats, and also no posts being emailed to comment subscribers.
Upon reinstallation and connecting to wordpress.com in order to use Jetpack features, the theme of the site breaks. Images overlap columns and becomes unusable. The moment jetpack is either deactivated (via plugin page) or disconnected from wordpress, the site returns to working layout.