Leadership is needed but the product has to be right too
I've been running Ubuntu as my main desktop OS for 4 years now and there is a lot I like about it. In so many ways I feel it's stil the most viable alternative to Windows and OSX and this surely has a lot to do with the strong direction that Canonical have imposed on its development. If Linux is ever to be a serious alternative for the average user, this is the only way it will happen.
However, with this leadership come - in my opinion - some mistakes. Unlike a lot of people, I don't hate Unity - in fact potentially I like it. What I do hate is all the things that still don't really work properly. On my machine - admitedly three years old but a fairly upmarket and powerful Lenovo Thinkpad - Unity is terribly slow. This is possibly something to do with graphics acceleration or something; I don't know and the point is I really don't want to have to know - I just want it to work properly. Similarly, the fact that the machine often overheats (and shuts down without warning) when doing backups or running VMWare, because the power management doesn't properly control the fan on my machine, undermines the experience badly. I also really dislike the incomprehensible behaviour of Alt-Tab, which is something I think Windows got right about 20 years ago.
My wife has a MacBook. What impresses me about it is not an amazing UI - it's good but not stunningly better than Ubuntu or even Win 7. What does impress me is the astonishing feeling of solidity and quality it exudes; everything is beautifully crafted, everything works smoothly and reliably, it almost never fails in any way. These things make it a pleasure to use and inspire a feeling of great trust and confidence.
The best thing Canonical could do with Ubuntu now is to stop trying to functionally change or enhance it, definitely don't waste energy trying to port it to tablets and phones, but just focus all their attention on polishing every little detail and making it work perfectly all the time. Then they'll have a real winner that MS should worry about.
Like others, I've been starting to notice that Mint looks very attractive. I think I'll install it on a spare disk and try it out but I don't want to swap one set of problems for a different set, so I'm not rushing into switching distro yet.