Qubes OS 4.0 was recently released after a fairly lengthy development cycle. https://www.qubes-os.org/doc/releases/4.0/schedule/
I have been running the new release on my Librem 13 laptop since RC3 and all the changes have been great. I am sure the release notes on their website will do a better job describing all of the changes than me. If you are interested you can find them here: https://www.qubes-os.org/doc/releases/4.0/release-notes/
My favorite noticeable changes were to the user interface. Widgets were added for mounting/unmounting USB devices, interacting with or shutting down running Qubes, and showing system disk space usage. Despite it being a controversial idea, the Qube Manager was slated to removed from this release. In the end the Qube Manager stayed, but with the addition of the new widgets I find myself rarely opening it anyways.
Purism has also released new firmware that supports Intel VT-d which is “required” in version 4.0. The update process was pretty straight forward on my Librem 13. I ran the update from a Debian Stretch installation I had on a 32GB flashdrive. https://code.puri.sm/kakaroto/coreboot-files/src/master/Changelog.txt
I previously wrote a short post detailing a business use case for running Qubes OS and would recommend anyone who wants better control of their data and security to give it a try.