It's not very often that Xfce gets a new release so today is certainly a rare occasion. The popular window manager is the main choice for those looking for a stable, no-frills desktop experience.
This release marks the completion of the project's transition from GTK2 to GTK3, something that has been in the works for a very long time.
In addition to this, there are some improvements to xfwm4, Xfce's default window manager. VSync support has been included with an OpenGL backend to remove flickering. HiDPI is now a base feature which is great since they are becoming more and more common in gaming. And to top it off, xfwm4 should play nicer with Nvidia's proprietary drivers.
With the timing of this release, it's also likely that we'll see Xfce 4.14 included in the upcoming Xubuntu LTS and derivatives (ie. Linux Mint Xfce) next April.
For a more complete view, check out the full release announcement