Well actually .. It's safe if you know what are you doing.
Don't try updating anything related with Xiaomi account , backup , cloud etc. Never update the SDK or apps "without icon" to say it simply.
If you want to update your gallery , dialer , browser etc it's safe but be prepared to maybe lose some features of these apps , but in this case just uninstall the update.
Be safe not sorry, always have a backup and an idea to reverse your updates or how to fix broken settings.
I can not recommend it if you are a beginner.