From the Microsoft blog post:
Changes, improvements, and fixes for Mobile
- This build also includes all the improvements from KB4016871 and KB4020102.
- The copyright date is correctly showing 2017 now under Settings > System > About.
- We fixed an issue where WhatsApp would not launch after updating to the latest Mobile builds.
- We fixed an issue with using the Japanese 12 Key soft keyboard where the “right arrow” key did not input a space
- We fixed an issue with the Bulgarian keyboard localization for the HP Lap Dock in Continuum.
- We have further improved the reliability of notifications for apps with a paired Bluetooth device, such as Fitbit.
- Improved the Time & Language settings page UX for Speech and Keyboard language downloads. Previously, the status would show “Downloading” for speech and “Installing” for keyboard. Unless, the user tapped on the language or navigated to the Update & Security settings page, there was no indication that a restart is required to complete the installation. Now when the update reaches the reboot pending state, a “Restart Required” is displayed under the language.
- We fixed several enterprise device management issues.
- We fixed an issue where notifications and Cortana’s cross-devices settings on your device were not being mirrored to your PC.
See my feature on upgrade paths for the various classes of existing W10M handsets and the wider grid covering older devices, even though most of these won't be able to take advantage of this (RS2+), even with the Insider programme.
Anyone with an existing phone that's officially deemed Windows 10 Mobile CU-compatible by Microsoft can join in the fun - in theory. In each case:
- Head into Settings/Update & Security/Windows Insider Programme.
- Join the Insiders programme and choose the 'Fast' level in the pick list.
- Within a few hours your phone should be seeing the build mentioned above and you'll be running the Creators Update and beyond...
Note that the popular Lumia 930 and 1520 haven't yet been 'provisioned' for this branch of Windows 10 Mobile. I tried - setting the Insider level to 'Fast' doesn't show up any of the recent 152xx builds. Do ping me if this changes, but I'm prepared at this point to say that these 2014/2015 phones may have reached their end on the Creators Update Release Preview ring, which will see critical updates through 2017 and then... no more after that.
See also my Windows 10 Mobile and the Future...