The latest build is out now for Windows Insiders in the Fast ring. Unfortunately, just like the previous build, it does require a rollback to 8.1 in order to install. Luckily, this should not be necessary any more in the next release.
To roll back to Windows Phone 8.1, you need to download the Windows Device Recovery Tool and run it with your phone connected via USB.
Once your Windows Phone is on 8.1 again, find and install the Windows Insider app and subscribe to the Fast ring. Reboot, and build 10572 should install.
What’s new in Build 10572:
Get missed call notifications and send texts on your PC with Cortana.
Cortana can book an Uber for you: just say “Book an Uber”. Cortana can also remind you of upcoming events, and help track your leisure time. Based on your location or movements, Cortana can now suggest where to go and how to get there (on time).
The Messaging app now supports animated GIFs, message search and contacts search within call history on the Phone app.
Save offline maps to SD card (top feature request fulfilled!).
Storage Settings: enabled the number one user feedback item for the storage settings page to allow you to install applications to expanded storage such as and SD card or USB drive on BOTH your phone and PC.