The Windows 10 "Redstone 2" test builds that have gone out so far haven't included almost any new features. Today's newest test build for Insiders using PCs follows in the same vein, with some minor new feature tweaks.
As with other Windows 10 test builds, there are other general improvements and fixes in this new test build around Narrator, app notifications, and personalization. And, as usual, there are a bunch of known issues, which anyone interested in running this build should check out before installing.
While on the topic of Windows 10 and updates, if you're one of those running the non-Insider version of Windows 10 Anniversary Update who got stuck in an endless-reboot loop when trying to install last week's Cumulative Update, there's now a scripting fix from Microsoft meant to help with that.