Earlier this month, the Linux Mint developer team released the Xfce edition of Linux Mint 18 'Sarah', which followed the main release at the end of June. But now it's time for some Plasma action, with a beta release of the upcoming Linux Mint 18 KDE edition.
It's worth noting that all three Linux Mint 18 editions are LTS releases (long-term support), with a promise to be supported until 2021. For that reason, these releases don't include bleeding-edge software, but instead software that can be assured to be stable right-out-of-the-box.
Tying into that, the recently released KDE 5.7 isn't bundled here; instead, KDE 5.6 is. Unless you're looking for richer Wayland (X window system replacement) support, you won't miss out on much. Nonetheless, if you do want the latest version, you'll be able to upgrade using the Kubuntu Backports PPA.
KDE aside, a major update with Mint itself comes by way of an overhaul of the update manager. It now supports alternative themes and has improved control over kernel updates. Upon launch, it now allows people to choose their update policy. By default, the policy will optimize stability and security, though you will still get regular updates for software.
If you're really concerned about stability because you use the PC as a mission-critical workstation and can't risk anything going wrong whatsoever, a 'Don't break my computer!' option is available. Finally, if you want to throw caution to the wind, you can allow Mint to update anything, anytime there's an update available. If one of those updates manages to break something, you'll be expected to fix it though.
Other improvements include an overhauled 'apt' command that behaves like the previous one in Linux Mint, while also supporting the same feature set as Debian's own apt tool, the inclusion of Thermald for temperature monitoring, exFAT and Btrfs support out-of-the-box, new artwork, and OEM install support.
If you want to give the latest version of Mint KDE a go, you can hit up the link and download. Be warned though that this is a beta release, so your mileage will vary. The final release is likely to drop in a couple of weeks.