The big wrinkle is still there
I read that Mint 17 will be the LTS version. I'm on MINT 13(maya) MATE but I tried Petra MATE in a VM and it still has problems when you try to use to side panels. If you have a left and a right panel, in MATE, then they get overlayed and messed about, so I settled on having just a left panel in my Maya installs.
This flaw shows up identically in all four, different PC/laptops I've tried it on. XFCE does not have this problem for some reason, but MATE has better facilities for my purposes so I use it.
Petra MATE does not show that problem but has a different problem, again associated with left/right panels and their contents. It looks like they fixed one problem and created another. What I find worrying is that I, a Linux noob and not a code-head, found these glaring problems within a short time of installing and trying to use the OS. Is there any substantial GUI testing done?