Before you get confused this is not the official release for the HTC One M8 rather this is the 8th Milestone build of Cyanogen Mod 11. This build comes with many new features, and is one of the most stable versions of Kit Kat from the CM team so far. This build is based on Stock Android Kit Kat 4.4.4. Cyanogen Mod did not post an official change log for this build instead they decided to direct users to an entire blog post highlighting all the new features that was posted a few weeks ago. You get all the security features that were released in 4.4.4 including a patch for towelroot.
Custom features and bug fixes include VPN fix, hidden apps with password protection (these hidden apps will also be hidden from all launchers not just the trebuchet launche), protected folders allow you to add password protection to apps without having to first hide them, Trebuchet GEL&CMHome, HeadsUp notifications (a floating notification panel, includes "do not disturb" setting for when in games), reorganized settings, and more!
Via CyanogenMod