This is a really interesting topic...Despite my low post count, I'm not a complete n00b; I have a lot to learn, but I've been running Linux for a year now, and I began the journey with Mint 13, so I feel compelled to chime in.
As others have stated, Mint seems to target a few different demographics:
1)
Transitioning Windows users, but not for the reasons we might think - Mint's success with this audience is predicated almost entirely on the streamlined and sexy, yet completely familiar layout of Cinnamon. Yes, Cinnamon is part of the Mint project, but you can install it on other disrtos. The fact that it's stock in Mint, means that when people research the distro, they're seeing screenshots of Cinnamon and thinking, "hey, that looks a lot like Windows', I can see myself using this". Mint wins the perception battle and passes the aesthetics test, long before people decide to even live boot it to test drive it.
2)
Jaded Ubuntu/Unity users - Ubuntu is a decent disrto...It's stable (sometimes), user friendly, and boasts a stable of really popular applications. Where Ubuntu and Unity fall short however, is that they seem to be trying to compete directly with MacOS. Unity has a flashy, unorthodox layout (maybe not so unorthodox for Gnome users), and that unfamiliar layout makes it unrelatable for the people from group #1. Unity also seems to be a layout that's better suited for a touch interface, which may turn off its existing users. I had this exact feeling when I test drove Ubuntu 13.04, and on top of the unfamiliar layout, attempts to install and use a different DE, will often cause Ubuntu and Unity to crash. Mint is Ubuntu done right.
3)
Gamers - Steam gamers often aren't considered in discussions like this, but they are a massive and ever-growing segment of the Linux population. I'd argue that the success of Valve and Steam will draw more users to the Linux platform, than a project like Ubuntu Touch ever will. Gaming is universal, and Seam is (currently) the only ecosystem that has cross-platform support - meaning Mac users can game with Linux and Windows users, and vise versa, whereas consoles don't provide this option. Steam runs perfectly on Mint (and Ubuntu), whch makes it an ideal distro for gamers.
4)
Low maintenance users - People who don't want to spend the time, forcing their system to do what they want. I just came back to Mint after a three month spell on Arch Linux, and I have to say that I have a new appreciation for the way the Mint team handles things. Updating Arch is an every day process, and obtaining new programs, often requires you to build them from the ground up. That's nice, IF you have the time, and IF you need that level of control...I don't. I like the fact that Mint tells me when updates are available, and how the GUI gives me visual feedback about which applications are "safe" to upgrade. It saves me a LOT of time, and keeps me from stressing over which programs may or may not be safe to upgrade. The only benefits I really gained from Arch, is that it's a rolling release (why Mint hasn't taken this approach is beyond me), and therefore, the packages are always the latest versions. I simply didn't have the time to babysit my Arch install, and I don't think many other people do either.
5)
Developers - I initially migrated to Linux for one reason - to build Android ROMs. While I suppose you could set up any Linux distro to do this, Mint and Ubuntu are the easiest by far. Google uses Ubuntu for their Android work, so most of the guides you can find, are written with those two distros in mind. I can set up my build environment, and begin syncing the repo in about 20 minutes. On Arch, I was facing at least an hour worth of package building and setup, before I could get to the same place...Mint simplifies the process.
While these are just MY ramblings and opinions, I do feel they're valid. I've tried Ubuntu 12.04, 12.10 and 13.04, Mint 13, 14, 15, and 16, OpenSUSE 12.13, and Arch Linux (with the Cinnamon 2 DE installed)... To date, I find Mint to be the distro that best suits MY needs; It has powerful tools, refinements to Ubuntu under the hood, a fabulous DE, a streamlined, minimalistic look that I enjoy, the ability to customize in almost infinite ways, it supports my hardware well, it's very stable, and it's low maintenance. These things are important to me, which makes ME (not a complete n00b) Mint's target audience as well. I think Mint bridges the gap between power users, new users, developers, and hardcore Linux enthusiasts perfectly. In my opinion, Mint is the best distro available, and it's not even close.
Just pulling your leg whilst I can.
