Linux Mint 13 is a Long Term Support or "LTS" release. This means that updates will be provided to users of Mint 13 and there will be no worrying about upgrading for several years.
Most distributions have several different desktop environments or "spins", but they only have one "official" release and as such that is the only one that gets long term support treatment. With Mint every desktop environment appears to be equally as "official" and so they all get the same support.

Mint 13 still has KDE and XFCE versions, but drops the GNOME version in favor of two new ones:

• MATE, a fork of GNOME 2. This version is almost exactly like Mint 11.
• Cinnamon, a fork of GNOME 3 that doesn't have any of the GNOME 3 desktop stuff. This version is almost like Mint 12.

These screenshots are of the MATE edition. Click on the next section link at the bottom of the page to see the Cinnamon version.

The MATE desktop looks just like the classic one did.

The menu is also now arranged the same way as the older Mint editions were.

As usual there are a few trade-offs. Depending on what theme I select I can only change a few settings. So if I were to change all the colors in the default theme to orange, the checkboxes and whatnot would still be green. And if I happen to select the WinME theme, I can't change any colors!