From the announcement feature list:
All Mint 10 features
Performance boost (using cgroup, the notorious “4 lines of code better than 200 in user-space)
Installer improvements (multiple HDDs, grub install on partitions, swap allocation, btrfs support)
Better fonts (Using Ubuntu’s libcairo, fontconfig and Ubuntu Font Family) and language support (ttf-wqy-microhei, ttf-sazanami-mincho, ttf-sazanami-gothic installed by default)
Better connectivity and hardware support (pppoe, pppoeconf, gnome-ppp, pppconfig, libgl1-mesa-dri, libgl1-mesa-glx, libgl1-mesa-dev, mesa-utils installed by default)
Better sound support (addressing conflicts between Pulse Audio and Flash)
Updated software and packages
Back to September 7th we saw the very first release, rather beta indeed, of this project, the first step to switch the distribution base from Ubuntu to Debian and to a rolling release policy.
Linux Mint is scoring place #2 at Distrowatch Popularity Ranking (well, kind of), just behind Ubuntu and before Fedora, OpenSUSE and Debian itself,
Only time will tell whether this is a winning move or not for Linux Mint. But why not giving it a run?