Xiaomi advertises the Mi Max as running MIUI 8, but that's still in Beta. Our review unit runs the latest official release, v7.3. It's based on Android 6.0 Marshmallow.
MIUI is one of the most comprehensive customizations of Android. It has a big following in China where Google services are not accessible so Xiaomi refocused the ecosystem away from Mountain View and onto its custom solution. For those living elsewhere, there are ways to sideload the full Google suite if the vendor hasn't done it for you.
The lockscreen is fairly standard (time, notifications, a couple of shortcuts), but once you setup the fingerprint reader you'll rarely see it anyway. Still, the Wallpaper Carousel can put beautiful images on the lockscreen every 15 minutes.
The fingerprint sensor proved quite accurate and can take the phone from sleep to homescreen pretty quickly (the lockscreen is bypassed). It's not as fast as some flagship implementations, but the speed is okay.
Tap to wake is available but off by default. We turned it on since reaching the Power key on a phone the size of the Mi Max isn't always easy.
MIUI has a simple philosophy - every shortcut, plus widgets of your choosing are dropped on the homescreen. You get a docked menu for the most commonly used apps and there's a search field in the notification area if you can't remember where you put a rarely used app.
The notification area has two panes. The first shows notifications (and the search field), swipe left and you get the quick toggles and the brightness slider.
The app switcher feels like it came out of iOS 6.0 - apps are represented by their icons, in a single horizontal row. Even on a 6.44" screen, you don't get to see a lot of apps at a time and you don't get to see a preview of the state in which you've left the individual apps. You can pinch zoom to switch to the standard thumbnail card view.
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.