what exactly do you see when you reopen it from the background? We had a bug where for example only the settings tab could be seen, but that has been fixed before 1.0 GA.
FYI The steps were:
1.Launch and configure the IOS client.
2.Login. Wait for the application to synch all files.
3.Disconnect the wifi.
4.Minimize the app, wait for few seconds(say 5-10) and then maximize the app.Notice that only settings tab is accessible (see snapshot)
Expected Result: User should be able to access the application offline.