This is How Xiaomi MI4 Running Windows Phone 10 Looks Like
Microsoft and Xiaomi has announced that they will be releasing Windows 10 for Phones ROM for MI4 users, and now in official thread, a real photo of MI4 running Windows Phone 10 has been posted up. Mind you that this is not a screenshot, but the actual OS running on the device.

Xiaomi and Microsoft China have worked together bring this for Mi 4 users, so they can enjoy the cool operating system without buying a new Windows phone. China is a huge market, where consumers love to install different ROM and customise to their need more than anywhere in the world. The official post said:
Wanna try out the latest features of Windows on your Mi 4? Stay tuned and we will release the ROM Pack soon in the MIUI forum. Always believe something wonderful is about to happen.
This is not going to be a public beta, but its only going to beta tested among Power Users to get solid feedback. The poll that is currently live shows that consumers have a great interest in trying the rom with 74% voting and counting. And if you read out the comments, there are MI3 consumers also wanting to test.
We expect the ROM to show up pretty soon, and I am sure Microsoft would want to have it tested before Windows 10 release this summer. Xiaomi could be a great hardware partner for Microsoft as it delivers better hardware specs at lower price.
