1. It's easy, both to install and to use;mrgoogle wrote:what makes linux mint different from other distros and what is the purpose of the project that separates us from them, that's what we should market
2. it's nearly complete out of the box;
3. it's long term supported (up to five years);
4. it's stable and reliable;
5. it has a huge amount of installable software in the repo's;
6. it even looks pretty decent out of the box;
7. it's a big distro with a huge user base and assured continuity.
Not surprisingly, only Ubuntu comes near. Mint just has it all. It's the best operating system on the face of the earth.
No need for bloody awful re-inventions of the desktop, which just cause a lot of annoyance because suddenly you can't find your applications or something.
A good desktop is an unobtrusive one, which has all the nuts and bolts in the expected places. It doesn't start singing and dancing in your face when you use it. So that you can launch your applications with the least possible amount of fuss, because in the end it's only the applications that really matter. The desktop is only a vehicle.
Mint does all this very well, with all its officially supported desktops. For God's sake let's not change that.