What turned me off was the disregard for the end user - from Canonical.
To me, they are using the Ubuntu community to test their Tablet / Smart Phone OS. Canonical is a company, no doubts about that, which means that in the end they have to care about their bottom line (making money)... again nothing wrong with that either. But, I think what a lot of users find insulting is that they are beta testing their products, without being open and honest about it, on a community that - they seem to forget - is a bit smarter than your "average" computer user.
I chose Mint because I was sick of Ubuntu's every-six-month-rush-rush-rush-realses. There's no sense in it.
Now, I don't necessarily thing Unity is a bad thing. A lot of hard core users hate it because it's change... and it is human nature to resist change. Do I think Canonical is going in the right direction? Sure, why not. Evolution is necessary for progression (you can quote me on that

). But, to release a version of LINUX without giving the user an OPTION (which is a synonym for Linux), which the mentality, “you'll beta test this for us and like it!”
I actually installed Ubuntu on my laptop and quite frankly it runs smooth... BUT as I have found. I can't install my Windows games without issues... so as we speak... Mint is going on the laptop. I will keep my Ubuntu partition on this desktop, because I've always like it. But, Mint is where it's at now.
And, yes, the Ubuntu community IS much bigger... but in the grand scheme it's pretty... I'll just come out and say it – worthless. You have to remember Ubuntu is huge and 80% of the now users can't tell the difference between Gnome and Firefox. Then those more expert users are so worn of answering the same questions over and over – that quite frankly the Ubuntu community (in MY opinion) isn't as good as the Mint – from what I've seen so far.
I know I am sounding negative, but that's not my intention. I just think Mint is a better quality OS that keeps true to the most rudimentary element of Linux – choice.
Canonical was – at that time – the best chance for Linux to really break through and challenge the close sourced options – but they blew it. And, I am guessing they may have set Linux back. BUT – then again I could be wrong. Perhaps their introduction into the tablet and smartphone world will bring more notice to Linux? Who knows....