This is mostly about the transition to SVG, not really a "brand evolution". The new logo is fine, not that much better or worse than any of the other variations shown. I don't get the hoopla.

I like what Wolff Olins did for Firefox OS and would love to see Mozilla take major new steps in that direction, with more radical changes to the logo (which frankly has always looked like a shrimp at favicon size): http://www.underconsideration.com/brandnew/archives/mozilla_...