Rated 4 out of 5 stars
I like this add-on a lot. I used to use gconf on linux to accomplish this, but that no longer seems to work with ff3, so firemacs was just what I needed.
One problem I've had is that I don't like the fact that it uses the X-Windows cut and paste buffer to store the contents of the emacs kill buffer. This is different from what I was used to when I used gconf, and I had built up a lot of habits that no longer worked. For instance, if I wanted to go to a web address that was on my clipboard, I used to click in the url bar, do control-A control-K, and then click on the middle mouse button to paste the new address in. Now that no longer works, because the control-K overwrites the X-windows cut and paste buffer. It would be nice if there could be a user preference setting to change this behavior.
I also didn't like the default keybindings, because too many of them overrode the standard Firefox ones (e.g., control-T). However, it was no big deal to get rid of all the ones I didn't want.