At first i had my hesitation upgrading from Mint 12 to Mint 13, as i wasn't sure if I should have gone Mate or Cinnamon
Gave a quick 5 minute review of each booting them off USB, and found out the path to Gnome "4" Mate is not as polished as Cinnamon, quite ironic considering Cinnamon is so "new" relatively speaking.
So, I proceeded to Backup my stuff from Mint 12, as per recommended by old time Mint Gurus, the restore was pretty much effortless.
So during install it asked if i wanted to install along side, or wipe the whole SSD or something else
I selected something else, as there is no option to Upgrade Mint 12 to 13, (it's not recommended by the way)
so i just selected the same partition where Mint 12 was installed, and it proceeded to install Mint 13 on top
it automatically imported my old user profile (all my data were in pristine conditions, including Firefox settings, etc) to my surprised it also automatically picked up the whole list of Apps that was previously installed in the system; and it proceeded to download and install as many as possible until it hit a minor bump with one that was not available in the repositories.
it finished the install, rebooted,and i was greeted with the new Cinnamon login & GUI
I've never had such a smooth upgrade before from 9 to 10, 10 to 11, or 11 to 12
oh and Mint 13 performs way faster than Mint 12 did on this old duo core 4 GB laptop, everything is snappy and launches right away
customizing Cinnamon was a breeze adding all the little add-ons to the menu, unlike Gnome, which was rather a pain sometimes to get some simple displays like CPU temp monitors added.
Thank you to the whole Mint Dev team