Late last night, I was able to get my hands on an unreleased build of Windows 10, 10108, that has several new UI updates over the last official release, 10074; you can check out that post here. After publishing that article, several readers asked for a full gallery, so here you go.
This build is not going to be released to Insiders and seeing that it is a bit unstable (more so than 10074), that's likely a good thing.
One item we were able to capture in the gallery below is the blue 'getting ready' screens. As we noted before, the 'Getting Started' splash screens no longer change color, they fade in and out of blue.
The updated toggles, more persistent dark theme throughout the UI, and updates to a few of the apps, all point towards further refinement. At this point, we would not expect any major feature additions to the OS (besides those already announced), as Microsoft is working on smashing bugs and improving stability as they march towards release.
I will keep digging around to see if there are any other changes to this build that we haven't already reported but if you have any specific questions, let me know in the comments below or on Twitter.