The first beta build of MIUI 6 ROM was released in February for the Xiaomi Redmi 1S. But this version wasn’t ready to be released to all the Redmi 1S users around the world. Now, months later the ROM is stable enough for other Redmi 1S owners as an over-the-air update. This news comes from Xiaomi’s official forum.
This long period of testing should have managed to take care of all the bugs. The full changelog is available here.
The version of MIUI currently going out is 18.104.22.168. Obviously it may take a few days for you to get a notification about the new build, but many people have already received it.
MIUI 6 it’s currently the latest iteration of Xiaomi’s UI overlay that sits atop Android. Up until now, the very affordable Redmi 1S was stuck on the older MIUI 5, unlike Xiaomi’s higher-end devices.