In a blog post announcing the rollout of build 10130, Microsoft's Gabriel Aul gave the rundown on what you can expect in this build:
As I mentioned with the last build, from here onward you are going to see a lot of tuning, tweaking, stabilizing, and polishing which means fewer big feature changes from build to build. You'll see that in this build which has a number of small improvements and more polish. For example – you will see some new icons (check out File Explorer) as well as many subtle changes to the UX. We heard a lot feedback around icons in Windows 10 and think these new ones are a bit more refined. Let us know what you think. We've also added new Taskbar animations for actions like moving files, downloads, etc. and more improvements to Start. And we also heard a lot of feedback around the border around Action Center – which is now gone in this build and looks much nicer.