* Messing up the marketing behind critical projects (Persona) and then shutting them down when their usage is too low for their taste.
* Axing Thunderbird, one of the last usable non-web-based email clients. I don't like nor use TB, but maintaining a decent email client cant be that hard for Mozilla, and it is important for the web.
* Putting a ton of money into Firefox OS, an atrociously bad and slow OS that had the worst mobile UX I've ever experienced. Then putting even more money into the Flame so that they can have a bad OS on dedicatedly-bad hardware.
* Constantly messing up feature development on Firefox with Hello, Pocket and more, all pointing to Mozilla clearly not understanding the Firefox userbase.
* In the mean time, Firefox is still far slower than chrome. Scrolling especially. Gmail and irccloud are unusable for me on Firefox. My own project hits Firefox's performance issues (compare seeking on this player in Chrome/Firefox: https://hsreplay.net/replay/vZEz7JoNnfgVo34HJUHhEF - Firefox is a solid 10x slower).
So to recap: Axing critical projects in a market they understand, so that they can spend the money on futile projects in a market they don't understand. Introducing controversial new features in Firefox while the browser is still far slower than Chrome, losing what's left of their market share. And this is just the big stuff, I could go on for another 10 paragraphs.
Mozilla is heading into a mountain. They need to seriously rethink their structure and priorities if they want to avoid a crash.
Edit/PS: Most of these issues are structural. Pocket's functionality is useful in a web browser. A truly-free mobile OS/smartphone is also something we need. And foss communications are extremely important to the web, which is currently locked in to hangouts/messenger. But Mozilla is messing all these up at every corner; underestimating costs, underestimating effort, misunderstanding (being disconnected from) their userbase, not marketing anything properly and giving up too easily.