Been using since release. I never felt like I was making some kind of compromise by using it. Firefox always had their shit together from my experience.

Now, it's on par with Chrome or better than (tradeoffs and personal preference), even for developing web apps. Firefox dev tools pull ahead of Chrome's, then Chrome catches up and does something new and useful, then Firefox catches up, and so forth.

Firefox is good. It's not like "I'm leaving Photoshop for the GIMP" kind of thing-- It's like "I'm leaving Honda for Toyota."