Yesterday Microsoft released build 10586 of Windows 10 Mobile which could well be the version that gets rolled out to Windows Phone 8.1 users as well as the build on the new Lumia 950 and 950XL. This build doesn’t have any new features but it does clear up the remaining issues with SD cards and seems a lot faster switching apps.
During the upgrade process I did hit the upgrade bug. This is a problem introduced in the previous build where it would corrupt the file system and then during the upgrade the phone would get stuck in a boot loop. So I did the key combination reset to get my phone upgraded.
So far the update seems very good for me, I am very tempted to put it onto my daily drive (a Lumia 1520). In this video I take a look at the new build.