Today's build may cause app and game crashing; error messages around updates being cancelled; and Narrator not working at all, according to the April 7 blog post outlining what's new. Those running Surface devices should especially be sure to check the notes before installing. The build also includes a number of fixes to some of the ongoing issues carried over from the Creators Update.
Redstone 3 is the next feature release of Windows 10 that will follow the Windows 10 Creators Update, aka Redstone 2. Redstone 3 is expected this Fall. Company watchers are expecting Redstone 3 to include Microsoft's MyPeople feature that was cut from the Creators Update, some improvements around Continuum, tweaks to the look and feel of the operating system and other new features.