While it is unexpected, this isn’t actually ‘Nokia going Android’. The Finnish company is using a forked version of Android, much like Amazon does with its Kindle Fire. It looks different, with a tiled appearance similar to Windows Phone 8, and at least for now it does not connect with Google Play services, instead integrating Microsoft and Nokia alternatives like Here Maps, OneDrive and Outlook.
You’ll be able to side-load apps via installers, but not through the Google Play store. As Google continues to integrate Play Services more deeply into Android, forked versions like Amazon’s and Nokia’s will find it harder and harder to run newer Android apps that use Play Services, unless developers adapt especially for them.
Nokia’s X devices are aimed at the cheaper end of the market, or as a stepping stone to its more powerful Lumia Windows Phones. This explains why it is using a version of Android that can run comfortably on low powered devices.