evo's John Simister explained how the LEAF won and basically why it shouldn't have. http://www.evo.co.uk/news/evonews/260515/2011_european_car_of_the_year.html
Reading that, I can see that he didn't want it to win, but I don't think he makes a strong argument that it shouldn't have won. One of his core arguments was that the Leaf rose to the top because the competition this year was unusually weak. I say: so what? In the land of the blind, the one-eyed man is king. If it's the best of the year, it's the best of the year, even if it's a weak year.
Otherwise, all I got was "I thought the C-Max should have won." I disagree. The C-Max is a well-executed but otherwise unremarkable compact MPV. The Leaf is a game-changer for the electric car market.
I'm not infatuated with the Leaf, but of the cars he discussed, I think the Leaf was the best choice.