Firefox has really become a big thorn in Microsoft's flesh and for that very reason many of us love this browser. I love it even more because it's just better in many ways and less prone to crash from my experience. Now what I never liked and have always been a bit weary of is the fact that Mozilla developed into a roaring money making machine thanks to it's search box. I have no objection to making money per se but when its uses are not really clear and you still actively recruit thousands of freelance open source developers to do your work on the cheap then that becomes an issue.
Read more on the controversy on the Guardian's blog or Valleywag.
Here's a link to the .pdf of the Mozilla foundation's financial statement