I use it daily, but Chromes dev tools are better. I always wind up back in Chrome to debug things.

One difference I've seen with FF vs Chrome is when finding the events to bind to each element. In FF, the event tag on the element is clickable and gives you the name and the line number in the JS file. It makes finding the code very easy. I have not seen that in Chrome. I rarely use Chrome, so this one thing leads me to saying FF's DevTools are better, at least for me and how I use them.

Funny, I have it exactly the other way around!