Since the Windows 10 Fall Creators Update was released in mid-October, there's only been one Insider Preview build to make it to the Slow ring. Build 17025 was offered on November 1, and the ring has been quiet since then.
Today though, Microsoft released Windows 10 Insider Preview build 17074 to the Slow ring, and it introduces a ton of new features, mainly because it's been so long since the Slow ring got any attention. Indeed, there have been five Fast ring builds since then, some of them quite significant.
Build 17063, which was released exactly a month ago, was probably the most notable of the five. It included headlining features like Timeline and Sets. Timeline allows you to go back to things that you were previously working on, while Sets lets you group UWP apps into tabs, similar to how a web browser works. Sets is still in control testing, meaning that not all Insiders have it yet, and it's unclear if Slow ring Insiders will get it right away.
You'll also notice some big changes in the Settings app, including a new design and some Fluent Design elements. Naturally, there are new options in Settings as well, as Microsoft is continuing to reduce the need for Control Center in Windows 10.
And naturally, you'll find many improvements in Edge, Cortana, My People, the Windows Shell, and much more. You can check out the changelogs from the five Fast ring builds here:
Unfortunately, if you're looking to do a clean install with fresh ISOs, those aren't available quite yet, although they should be soon. The 17025 ISOs were made available on November 7, six days after the Slow ring release.