The Xiaomi Redmi 4 Prime comes with Android Marshmallow and MIUI 8 on top. It has a big following in China where Google services are not accessible, so Xiaomi refocused the ecosystem away from Mountain View's services. For the time being there isn't an international ROM for the Redmi 4 Prime, but the unit we have for review happily ran the Play Store and the rest of the Google suite.
The lockscreen is fairly standard (time, notifications, a couple of shortcuts), but once you set up the fingerprint reader, you'll rarely see it anyway. Still, the Wallpaper Carousel can put beautiful images on the lockscreen every 15 minutes.
The always-on fingerprint sensor proved quite accurate and can take the phone from sleep to homescreen pretty quickly (the lockscreen is bypassed). It's as fast as some of the latest flagship implementations, but that's not really news anymore - everybody seems to have a good reader these days.
MIUI, like most any Android overlay out of China, has a single-tiered interface - every shortcut, plus widgets of your choosing, are dropped on the homescreen, without an app drawer. You get a docked menu at the bottom of the screen housing the apps that are always accessible. The homescreen also supports wallpaper carousel, you can enjoy different beautiful wallpapers all the time.
Themes are fully supported, and several are available out of the box. You can download more, they change wallpapers, lockscreen style, system icons, and font, sounds too.
The notification drawer sees the biggest visual change, with a consolidated list of quick toggles, notifications, and a weather panel at the top that changes color and animation according to the weather.
The app switcher feels like it came out of iOS - apps are either represented by their icons, in a single horizontal row or by appropriate thumbnails in the same manner.
The highlights of the new features, part of MIUI 8, are Dual Apps and dual spaces. Dual Apps allows you to have two instances of the same app on your device, so you can, for example, have two WhatsApp accounts on the same phone, one for each SIM. You can have two instances of any app.
Any app can become a dual-app - you just need to enable it from settings. The second instance has a yellow indication on its app icon, so you'll always know which instance you are opening.
Dual spaces let you have two different workspaces on your device, each with its own set of apps, customizations, and image gallery, and you can enter a custom passcode or a different fingerprint to enter either of the space.
Configuring the second space is very easy and straightforward. After setting a different PIN and/or fingerprint, you can import and share photos, files, and apps between the two spaces, or choose to keep those entirely separated. You can also opt to view notifications from the other space so you won't miss anything.
Switching between those spaces is hassle-free (you even get a Switch shortcut in the notification drawer), but far from blazing-fast. We complained in the Redmi 3S review that its Snapdragon 430 and 2GB RAM weren't quite up to the task, but the Snapdragon 625 and 3GB of RAM here don't make much of a difference.
Quick Ball can pop up to 5 shortcuts, and you can put here pretty much anything - from Android actions to app shortcuts. The Ball can also hide automatically on chosen apps, and move aside when you are running a fullscreen app.
Finally, the MIUI 8 supports scrolling screenshots - the feature lets you take a screenshot of an entire page by scrolling and combining multiple images into one long screenshot that you can then crop to your liking.