A week after the previous build (15055) we have a brand new Windows 10 Mobile version, build 15063, for all those on the 'fast' Insiders ring - highlights are more bug-fixes, but then we're getting ever closer to a first production build of the Creators Update (Redstone 2). 15055 was a 'good'un for me and this should be even more stable, perhaps even the one that eventually gets pushed to 'production' status smartphones across the world. Of note is that language and speech packs are now enabled again, often the sign that Microsoft is finished changing the underlying OS and APIs (for the time being).

From Microsoft:

Today we are excited to be releasing Windows 10 Insider Preview Build 15063 for PC and Mobile to Windows Insiders in the Fast ring.

Other changes, improvements, and fixes for Mobile

• We fixed the bug causing a number of inbox apps to fail to launch (such as Store) and also preventing any app updates from the Store from working. Thank you all for sending us feedback around this.
• We fixed the bug causing background tasks to not run in the background like they should such as OneDrive’s camera roll sync feature. Background tasks should be working again as expected and your camera roll will sync to OneDrive again.
• We fixed the issue where in some cases you may lose your call, text, and email history may be lost if your device experiences an unexpected reboot.
• Speech Packs should download and install normally.
• We fixed an issue for Insiders with certain cars resulting in connection failures after pairing Bluetooth.
• We fixed an issue where replacing the default APN for LTE on the phone wouldn’t work.

Known issues for Mobile

• Updating from the Windows 10 Anniversary Update (Build 14393) directly to this build won’t work. There will be an extra hop required to get to this build. If you use WDRT to go re-flash your device and join the Fast ring, you will not be offered this build and instead offered Build 15055. Once you’re on Build 15055, your device will find Build 15063 and take the update then.
• Some users are reporting that pages are constantly reloading or refreshing, especially while they are in the middle of scrolling them in Microsoft Edge. We’re investigating.

Plenty that's notable above - working Store updates and background tasks are a cause for celebration. At last.

Even after official 'release' of the Creators Update, a genuine line in the sand for Windows 10 Mobile, I'm still expecting some extra 'Release Preview' builds to tidy final bugs up through April/May. Which means that at some point soon after the Creators Update hitting, many 'Fast' ring Insiders here might like to consider switching to that (RP) ring, otherwise you'll start to get shunted off into Redstone 3 early builds, and those will be pretty unstable for a while. Just something to think about if the relevant device is your daily phone.

See also my summary of what's new going from Redstone to Redstone 2 (Anniversary Update to Creators Update).

Anyone with an existing phone that's officially deemed Windows 10 Mobile compatible by Microsoft can join in the fun. The full list of phones includes Lumia 430, 435, 532, 535, 540, 635 (1GB RAM version), 640, 640 XL, 730/735, 830, 930, 1520, Icon, BLU Win HD w510u, BLU Win HD LTE x150q, and the MCJ Madosma Q501. Plus, of course, all the devices which have shipped with Windows 10 Mobile in the last year, of which the Lumia 550, 650, 950, 950 XL, Acer Jade Primo, Alcatel IDOL 4S ('with Windows 10') and HP Elite X3 are the highest profile.

In each case:

1. Upgrade to Windows 10 Mobile (if appropriate) using the Upgrade Advisor.
2. After at least one update cycle you should then be on the Anniversary Update (a.k.a. Redstone). Head into Settings/Update & Security/Windows Insider Programme
3. Join the Insiders programme and choose the 'Fast' level in the pick list.
4. Within a few hours your phone should be seeing the build mentioned above and you'll be running the Creators Update - today!