MIUI is Xiaomi's forked version of Android and version six has just been updated for the Xiaomi Mi4, released in India last week. Although the English version of MIUI is only available on the one device at the time of writing, it'll be coming to a whole range of devices in the coming months. Now, MIUI is a forked version of Android that as standard does not come with Google Services. And let's not forget I recently penned an article discussing how one of Google Android's threats was essentially from other versions of Android. I need to clarify what I mean when I write "Google Android;" what I mean is "Android that has Google Services pre-installed." That means the device has the Google Play Store, Google Services, Gmail and Google Maps applications fresh out of the box. Devices that run Android without Google Services still run Android, merely a different flavor. MIUI comes without the Google Services as standard although it'll happily use them if you want it to. MIUI 6 is based over Android 4.4 KitKat: Xiaomi are working on building MIUI over Android Lollipop, but it won't be ready until at least April.
As an overview, MIUI has a real sense of familiarity if you've picked up an Android device (or for that matter, an iOS device). MIUI is as different as it is similar to stock Android; there are different icons and animations plus a built-in theme engine with over eight thousand themes available, so the problem is less about there being a theme you'll like and more about finding it! Stock Android doesn't have a theme engine, although some third party alternatives offer this.
Xiaomi's built-in applications look different from stock Google Android applications, but then most skinned Android devices have changed applications too! MIUI handles notifications a little differently: there's a list of applications that always have their own notification space, such as the email, text messaging and calendar. But other applications are given a shared space for their notifications. In practice, it does a decent job of cutting down on the excessive notification clutter that I can sometimes experience with stock Android if I am working on my device and trying not to be distracted by notifications. Before I know it, I'll have the Google Docs offline file, Google Play Music, Hangouts and Gmail notifications; MIUI groups many of these together for a cleaner look.
Xiaomi have included a cache Cleaner tool plus a Virus Scanner. The Security application allows you to take a deeper look at what permissions individual applications want. It also gives you finer control over what applications launch when you restart your device, too. I can add these functions to stock Android with a visit to the Play Store if I need to whereas Xiaomi provide them as part of the operating system.
Xiaomi have worked on developing their cloud-based services, including relocating these servers outside of mainland China for trust reasons. You get 5 GB with Mi Cloud, which allows you to save and synchronize contacts, text messages, photographs, call logs and notes. In some respects, Google offers a better service here as you get 15 GB of storage with a Gmail account, but you need third party applications to save text messages and call logs, whereas Xiaomi's MIUI performs this right out of the box.
There are some features that are only available to Chinese customers at the moment such as the ability to mark callers as spam and interactive price guides when calling restaurants. Xiaomi's work with local businesses and the user community needs to be duplicated across the world for the same quality of service and it would be interesting to see the Mi Cloud services rolled out across the world. The best we can hope for is a "watch this space."
Bringing things to a conclusion, a few paragraphs above I wrote that I sometimes suffer from a glut of notifications from a number of Google Services. MIUI handles these elegantly... but they must be added. Using MIUI without Google Services was a challenge, but it was easily rectified. And once I did this, MIUI felt more like the kind of operating system I could use day by day.
Because of this, I'm not so sure I can consider MIUI a threat to Google Android for the customer who wants Google Services. What MIUI allows customers to do is get into the smartphone world without accessing and relying on Google Services, just as iOS (and Windows Phone, BlackBerry 10 do, but these platforms are significantly smaller).
I'm reminded of the golden rule about any particular platform, be it console, computer or wearable device. Get whatever allows you to run the applications you need.