I used Chromium on Linux for 2+ years and switched back to Firefox during the 4.0 beta cycle. I'm much happier with Firefox's extensibility and interface and I haven't had any major issues since going back. The main reason I used Chrome was because it was so much faster in terms of WebGL and JS execution, but now that Firefox is regularly improving and competitive, I am much happier with the experience.
I had to switch to FF 7 (clean install, no addons) for one full day yesterday, and it feels so much slower than Chrome.
I used to be a huge FF advocate, until Chrome arrived. At first I stayed on FF and tried Chrome a couple of times. It lacked AdBlock back then, so I didn't switch immediately. There's no way I'm going back to FF now.
