Oh boy this has been a tough go around for me with the Cinnamon and Mate DE's, and it boils down to this, plain and simple, neither are ready for prime time yet. If I am offending any Mint Linux folks out there, oh well :_(
All I can tell ya is that both are very buggy, and that's expected considering the relative newness of each environment. I have high hopes for Cinnamon, I truly believe it will one day become a truly outstanding User Interface for the Linux OS.
The Mate DE, unfortunately I believe is loosing ground fast, perhaps in the hands of the Mint Linux team they can pull off a miracle, and eventually combine the two of them into one coherent Desk Top, as it stands right now the amount of conflicting LIB's, although rather small seem to cause very bizarre behavior once combined.
Both Mate and Cinnamon are forks of Gnome 2, and each has their own idea's of what is good, and what's not. For instance the Mint Menu extension ( exclusive to the LinuxMint distribution ) is horribly broken, slow as a snail, and completely worthless as far as editing the actual menu is concerned. For that matter Mint 17 ( the folks that are heading up the Cinnamon project ) feels extremely bloated and sluggish in comparison to just about every other DE I have tested so far, besides Gnome,Unity and the stock KDE. Believe it or not those are even worse, but at least they are not hopelessly broken, and once you figure out how to turn off all of the completely worthless Eye Candy Crap, you end up with a workable UI on all 3. Mate and Cinnamon are both broken right out of the box :_(