I am also wondering what exactly 'background sync' means. I assumed that if I modified a note on my Mac, it would, eventually, make it to the iOS app without me having to open it. Then I wouldn't have to worry about opening and syncing before I leave the house/wifi. I understand that background sync clusters together data transfers, but I in once case I didn't open the app in over a day and it still hadn't synced even though it was 'running'. Also, I gather that iOS 7 learns what you use and background syncs appropriately. If this is the case then I'm not sure if iOS 7 itself is to blame, the Evernote backend, or the Evernote app. You would think it would at least attempt a sync once every few hours if there is new data available. I hope they will work it out sooner rather than later.