Until recently that is. I saw the mockups of firefox 4 and liked it instantly. The second it was in the Arch Linux repositories I installed it and started using it as my main browser instead of opera or chromium.
Sadly there are some issues with it, especially with flash. The other issues were just annoyances that were fixed with about:config changes. (Not that I'm blaming the folks at Mozilla for this, there is a high chance its Adobe's fault...)
For some reason some websites using flash display fine but others go haywire and parts of the flash disappear or flicker.
One suggested solution I found was to do the following:
1. Click Here
2. right click on player
3. click settings
4. choose left-most tab
5. uncheck "Enable Hardware Acceleration"
However this only worked for some people but not for me.
There is a pre-release copy of Adobe Flash Square in the archlinuxfr repository (I presume most Arch Linux users have this for yaourt), and installing this, which prompted me to remove the existing copy of flash, and restarting firefox fixed the issue for me completely.
For those with archlinuxfr:
bash$ sudo pacman -S flashplugin-prerelease
or to get archlinuxfr add the following to your /etc/pacman.conf in the appropriate section.
# The french Arch Linux communities packages.
Server = http://repo.archlinux.fr/$arch
EDIT: After a security hole was discovered the package was pulled but due to a new release, the package is back in the AUR as flashplugin-prerelease at version 22.214.171.124-2 as of today. I'm unsure as to what version is in the archlinuxfr repository currently but I assume it will be older than the one in the AUR.