MIUI 9 on your device will be updated to its stable version. It's better than the Developer ROM you're using right now in terms of stability and productivity. However, here are a few points you should pay attention to:
1. Root access will be turned off automatically after you update. (And nothing will change if you haven't been using it in the first place). If the apps you use frequently need Root access, think whether you should choose not to update your device.
2. Stable ROM outperforms the Developer ROM in terms of stability and productivity. Moreover, it offers additional features (e.g., App vault) which were not available before. Note: Some new features might not be available due to compatibility or other reasons, but this wouldn't affect your overall user experience.
3. Your data won't be affected by this update. We still recommend to back up all important items to Mi Cloud or your computer before you start updating to avoid possible data loss due to abnormalities and unexpected errors.
4. Automatic updates will be turned off after this update. For next update, go to Settings > About phone > System update, and tap "Check for updates".
New - Simplified the UI(10-31)
Highlights
New - Improved layout and readability for search results in Contacts(06-29)
New - Virus scans and payment scans were merged into Security scan(06-29)
New - Better blocklist rules with the possibility of separated rules for every SIM card(07-10)
New - Switch for turning Battery saver automatically when charged(07-19)
New - New display formats for update logs in Updater(07-25)
New - Search for apps in the Dual apps settings(08-03)
New - Quick ball goes back to the edge after 3 seconds of inactivity(08-30)
New - All-new Mi Drop(09-26)
New - Mi Mover, supports data migration restarting. During migrating data to the new phone, device hotspot connection will be restored automatically in case of interruption to complete the data migration.(10-25)
Optimization - Protection from unintentional tapping for Dial pad(08-08)
Optimization - Redesigned home page(08-24)
Optimization - Devices with rare Bluetooth profiles are hidden in the device list(08-29)
Optimization - Simplified and improved the design of the virus scan result page(09-07)
Optimization - Hide free and incompatible themes in the list of the purchased items(10-10)
Optimization - "Add to favorites" icon adjustments(10-24)
System
Optimization - Increased system decryption speed(06-23)
Optimization - Increased system decryption speed(06-23)
Optimization - Devices with rare Bluetooth profiles are hidden in the device list(07-25)
Optimization - Devices with rare Bluetooth profiles are hidden in the device list(08-29)
Fix - Apps changed Wi-Fi connection status without the user's permission(06-23)
Fix - Apps stopped working in the background(06-24)
Fix - Only Mi TV/Mi Box can be added/shown on Mi Remote app after the update.(08-22)
Fix - WhatsApp force closed in Split screen(08-29)
Fix - Long pressing soft buttons lead to FC issues(09-19)
Fix - KRACK WPA2 security vulnerabilities(10-19)
Phone
Optimization - Vibration no longer affects the features which reduce ringer volume when the phone is lifted or flipped to silence (10-10)
App Lock
New - Added the App lock step before unlocking using a new fingerprint for the first time(08-15)
New - App lock supports hiding messages from selected apps(10-31)
Contacts
New - Improved layout and readability for search results in Contacts(06-29)
Optimization - Protection from unintentional tapping for Dial pad(08-08)
Messaging
Fix - OTP messages were grouped with notification SMS(06-16)
Fix - Time in Messaging didn't change when the system was switched to 12-hour format(08-29)
Fix - Messages with one-time passwords disappeared(09-07)
Fix - Messaging force closed in some cases(09-27)
Lockscreen, Status Bar, Notification Bar
Optimization - Vibration for notifications during calls(06-16)
Optimization - Notification shade response(07-04)
Optimization - Adjusted time for tapping the Lock screen notifications(10-24)
Fix - The search bar in the Notification shade wasn't displayed correctly(06-27)
Home screen
Optimization - Users can set their main Home screen in the editing mode(08-29)
Optimization - Multiple themes supported on the clock widget(10-19)
Optimization - Move app icons into a folder easier(10-19)
Optimization - Adding widgets to an empty spot with a single tap(10-31)
Themes
Optimization - Redesigned home page(08-24)
Optimization - Updated Peach blossom and Asphalt themes(09-14)
Optimization - Hide free and incompatible themes in the list of the purchased items(10-10)
Optimization - Themes prompt about connecting to the internet when it's required(10-12)
Optimization - "Add to favorites" icon adjustments(10-24)
Fix - Previews in recent wallpapers rotated(09-20)
Camera
Fix - Language support issues(09-12)
Gallery
Fix - Image has been compressed multiple times(10-19)
Backup
New - Mi Mover, supports data migration restarting. During migrating data to the new phone, device hotspot connection will be restored automatically in case of interruption to complete the data migration.(10-25)
Fix - Mi Mover can't continue to migrate data after the network connection is interrupted and restored(10-25)
Fix - Mi Mover can't migrate all apps to the new phone(10-25)
Settings
New - Search for apps in the Dual apps settings(08-03)
Optimization - Reduced multiple steps for discovering Bluetooth devices(06-07)
Optimization - Input method animation appears after when search bar is tapped(06-07)
Optimization - Introducing Button and gesture shortcuts(09-15)
File Explorer
Fix - The number of docs in Explorer was shown as 0(09-27)
Downloads
New - Downloads keep waiting when the connection is established again in case it was interrupted(09-05)
Recorder
Fix - Adjustments for Recorder and Second space(06-23)
Calendar
New - Holiday cards for Russia(06-28)
Mi Account
Optimization - Reduced the number of push notifications when the user is signed out(10-30)
Mi Drop
Optimization - Received files are sorted by time(11-06)
Fix - Issues with loading big GIFs(11-06)
New - All-new Mi Drop(09-26)
Fix - Transfer status wasn't displayed correctly when a file participated in multiple transfers(10-12)
Fix - The app crashed while transferring a large amount of files(10-12)