Today, the KDE and XFCE flavors of Linux Mint 17.2 Rafaela have been released, being powered by Kernel 3.16, the same kernel used by Ubuntu 14.04. Linux Mint 17.2 will be supported until 2019 because it is a long term release.
The KDE Flavor uses KDE 4.14.2 but with some Linux Mint specific customizations, while the XFCE flavor uses Xfce 4.12.
Among other enhancements implemented, the Update Manager and the display manager have been improved and the system has received better support for UEFI, Nvidia and Optimus cards.
As a reminder, the Linux Mint developers have decided to build their future Linux Mint systems on LTS versions of Ubuntu only, so Linux Mint 17, Linux Mint 17.1, Linux Mint 17.2 and Linux Mint 17.3 will be all based on Ubuntu 14.04 Trusty Tahr. This way, the developers have more time for implementing Linux Mint specific software.