Mother Fucking Style Changes
Mother fucking Mozilla, fucking stop changing the bloody style already

I get it; you like this fast update thing. But fucking stop it, at least with the style change. I grow used to how the browser looks, and then you are changing it once a month. Please stop.
Now I will have to update my skin again, via Stylish, to get the buttons at the top to look somewhat familiar again.
Mainly in the fact that they're on a version update high right now, pushing out major version changes when nearly nothing actually gets changed. They seem to be changing versions just because "updating so often is popular, and is what that other browser Chrome does". Sorry, but if you ask any Chrome user, I can guarantee you that they do not use and like that browser because "IT UPDATES REALLY FAST!"
Aside from rapid major version changes, I don't have many complaints. Other than some smaller things are changing so fast with each version (like the newtab page and button style changes).
Pinned Tabs are nice. A mutilated version of Pinned Tabs that gets semi-castrated at regular intervals is NOT... especially when they literally refuse to add prefs to control the bizarre, unintuitive, and unnecessary behaviors!
I'd introduce a bug to implement Pinned Tabs as a separate feature free of the "app" bullshit, but I'd either get ignored, laughed out of the place, or slapped with a WONTFIX. Or maybe they'd plan a fix for 2014. Ugh.
I just love and use Firefox because of the enormous customization it offers. I've grown rather particular about how certain things function and behave, and Firefox lets me browse just how I like
Chrome was originally loved since it was blazing fast and lightweight. But I've heard from a number of people that after they collect a number of extensions, the memory usage and performance really goes down the toilet. Which makes sense, since as you add on more extensions and things, the browser is doing a lot more.
So I get that, and try to keep my extensions limited. But there's just some I can't live without
Also haha, yeah I use a ton of JavaScript bookmarklets. I have a whole folder full of them. Some I got from the internet, others I built myself. I absolutely love them, and since they're usually browser independent, you can run them on any browser you want.