The main thing to know about new Mi Band: you need to upgrade your firmware to the latest version with the official application. Preferably, with iOS application.
During Sunday, October 25th the application will be back in Store. You won't see many changes, but the new version of Mi Band is handled by it more gracefully. Also, there are some internal strategic improvements.
- alarms are not working
- sleep is not tracked
Known issues with new firmware:
- band location feature doesn't work