Comment 21 for bug 769874

Not only that, the license is clearly not a free software license (as in freedom). Although the free software foundation hasn't said a word on it, I've conducted an analysis into it:

Suppose Mozilla Firefox were under this license. Forks like Iceweasel would have to be named "Firefox derivative Debian" or something similar. But the Mozilla trademark policy doesn't allow this, because the trademark and Firefox have both been modified. In this case, Canonical's trademark guidelines prohibit use of the Ubuntu name in commercial distributions. You must have the freedom to charge any price you want for free software.

In other words, the license grants no rights under trademark law, and yet it requires you to use the trademark if you make trivial changes. In virtually all other licenses, if the trademark policy doesn't work for you, you can just get rid of the trademark, but this license doesn't allow that.

For the freedoms of free software to be real, they must be permanent unless you do something wrong. In this case, one of your important freedoms can be taken away at will with a trademark, and therefore the license is non-free.