Not to rock the boat here but isn't Linux Mint a derivative of Ubuntu?
There is SO MUCH confusion when it comes to Linux distros because some say this distro is better, other say that distro is better. It all boils down to a very confusing mess of "he said, she said".
Who is right? Which distro is better? Depends on the day of the week and the weather if you ask me. One person advised me that Mint 10 sucked, that Mint 11 was way better, then another said the exact opposite. The Ubuntu was great but Mint sucked. If the Linux community is having this many issues regarding distros, then it's no wonder that everyone else is so confused.
There's lots of others derived from Ubuntu, but not by the same developer. That's what makes up for the difference, things are changed around, other things are improved, and they didn't really improve on how bulky Ubuntu is for computer resources. The only reason people use it is because it's an easy migration from a Windows OS to Linux, and it's also more widely known. Same reason why the majority of people use IE... Firefox doesn't come pre-installed on your machine (more than likely), and same thing with Iron or Chromium.
Sabayon and OpenSuse are far more superior than Ubuntu, as the same with Arch.
Mint 10 is bad, and same with Mint 9, Mint 8 was better than 9, and Julia was horrible in comparison with 11. As stated, Ubuntu is easy to use, which is why some beginner Linux users will always tell you that Ubuntu is better. But that's probably only on a user configurability level.
They aren't having many issues at all, it's Open source, the development on Linux will surpass Windows at some point i'm sure, unless they all give up and the kernel goes down the drain.