I haven't been impressed with their actions over the past few years.
Just look at Firefox. Instead of striving to provide a lean, practical, extensible browser, all they've managed to do is copy Chrome as of late. The UI changes have not been for the better. The release schedule changes were very painful, and the version number inflation is pointless. While its performance and memory usage is marginally better these days, it has still been years without any significant improvement. It's not surprising that users are moving away from it to other browsers.
Then there's Thunderbird. Aside from Firefox, this was one of their only other pieces of useful software. Yet they've dropped their support for it to a minimal level.
What's worse, while neglecting their software that people actually use on a daily basis, they've embarked on pointless efforts like FirefoxOS and Persona. We don't need another mobile OS, especially one that's essentially crippled to only supporting development using HTML5, JavaScript and CSS (which, of course, are already available on Android and iOS, not to mention the other mobile OSes that are already widely available). Persona is clearly not gaining any traction.
The only encouraging thing out of them has been Rust. But even that seems to be rather loosely associated with them, and appears to be regarded as quite experimental.
I know, I know. I'm not paying for their software, so they don't have any obligation to me, etc., etc.. I'm merely not convinced that their actions really correspond to the principles in their manifesto very well.