If you're curious about the new features in this build, you can check out this blog post at the Windows Blog.
One of the interesting new features is the Ultimate Performance power profile. This is designed for Windows 10 Pro for Workstations and aims to eliminate micro-latencies that are introduced by fine grained power management techniques.
Microsoft warns this is an early release, so testers should be aware things are a little rough around the edges, as is usual for a build at the beginning of the development cycle for a new Windows 10 release. To get this build, you need to be part the Windows Insider's Fast Ring.