While the hardware and performance of the Mi 6 are both decently positive, the software is another story. If you will recall, when I reviewed the Mi Note 2 in February, I was not hard on MIUI 8. While the Marshmallow base was not ideal on that phone, the software experience didn't seem too negative. And in comparison to other companies' "skins," MIUI still isn't all that bad. But unlike the black sheep of the past, like TouchWiz and EMUI, MIUI has not changed. At all.
On the Mi 6, the Android version underneath has been updated to Nougat 7.1.1, which is about the best I can say. The notification problems, Bluetooth connectivity reliability (rather, the lack thereof), and power-saving measures are still here and ugly as ever (they showed up on the Mi Note 2 shortly after that review was published). They interfere with usability, sometimes severely, and create far more problems then they "solve." I find that many of the decisions are just stupid, such as not allowing apps to be exempted from the power-saving stuff (e.g. Android Wear, Pushbullet, Tasker); even if you tell the OS to ignore those apps for battery optimization, you will find them back in the "Not Optimized" list after clearing the settings from the recents menu or rebooting.
Like with the Mi Note 2, my Mi 6 review unit defaults to the MIUI 8 global beta weekly builds. While updates do not, in fact, happen every week, they are still frequent enough — and most of the changelogs simply state "Fixed some bugs." Android version bumps are usually slow-coming from Xiaomi, but monthly security patches and such are frequent.
Software design has become very important in recent years. It makes sense, really; who wants to look at an ugly interface several times a day? It's a huge bummer, but MIUI looks and feels quite stale and bland at this point. Even Huawei's EMUI looks fresher and cleaner than ever, but MIUI appears the same now as it did a year ago.
Using the Mi 6 is boring, mostly due to the unoriginal, uninspired software design. This feeling of outdatedness persists through every level of MIUI.
All of the customization options are still here, obviously. One of my favorite little touches is the weather in the notification shade. It's simple and rather unimportant in the grand scheme of things, but it's the little stuff that counts. The header color also changes depending on the time of day and conditions. You can also choose the order of the capacitive keys, whether you want the normal or Samsung (wrong) way. Other staples like Second Space (which allows you to create a second instance of an app for login purposes), App Lock, and the "battery issues analysis" are all present. And yes, the stock launcher still lacks an app drawer.
Notifications remain a sticking point for MIUI. They don't work well at all. Even though it's now based on Nougat, the software won't let you expand notifications in the shade or on the lockscreen, the app icons for each notification continue to clutter the status bar, and Nougat's bundled notification magic is very obviously missing. In short, this part of MIUI is a mess just like it was a several months ago (and when it was based on Marshmallow). Oftentimes, notifications won't even come through because of the atrocious battery saving measures — such times require you to go into the app you want (like Gmail, Slack, etc.), which finally triggers the missing notifications. When you rely on the relative reliability of new emails pushing through when they arrive, this behavior is very unacceptable.
Bluetooth is another spot where MIUI drops the ball. Both of my Android Wear devices and my Gear S3 Classic repeatedly disconnected; each of my Bluetooth headsets and speakers would either fail to pair or drop connection during playback. The latter makes the lack of a 3.5mm jack all the more painful (especially since I never remembered to bring the stupid adapter with me everywhere I went). I don't know whether this is an issue with the implementation of Bluetooth 5.0 with the Mi 6 hardware-wise or something in the way MIUI is handling the standard. What I do know is that it's very, very annoying.
Beyond these specific issues, MIUI is just plain, bland, and outdated — something with which Jeff agreed in his Mi Pad 3 review. And the fact that it's missing some of Nougat's features like bundled notifications and multi-window is utterly sad. Come on, Xiaomi.