Some problems with Mozilla are that they don't do community management well any more. In the old days, there were amazing grassroots-driven projects like spreadfirefox.com. It is not like that any more. Grassroots supporters have trouble participating, even if they try.
For example, I tried to create a Firefox programmers' meetup group in Berkeley, and even though some community people from Mozilla joined the group, no one from Mozilla would reply to my inquiries. (I still would like to restart that idea, but I don't have time to chase them down. We have 4,000 members in our various meetup groups at the moment.)
Another problem is that they are doing things that make their most-dedicated core users lose interest. They should have realized the incredible enthusiasm for Firefox that plugins like Pentadactyl were creating. They're killing off the API that it depends on. Instead, they should have funded the development of Pentadactyl and made it a reason why tech-savvy users choose Firefox. Tech-savvy users drive adoption, but they have abandoned many of their tech-savvy supporters.
There is still hope for Firefox if they are able to get the messages about privacy across. Chrome is slower to use out of the box, partially because of the auto-completion algorithm that tends to send people to Google Search to click on ads before reaching their destination. The older Firefox search box didn't waste users' time like that. (Recently it changed so that it shows titles rather than URLs, which is also slow, because there is an extra security risk of going to phishing sites, if you don't stop to look at the URLs.)
Also, Firefox is the only mobile browser that allows add-ons, so that's another benefit that they should be promoting.