I've used smoothwall for a while and I was very satisfied with it. But at some moment, it stopped working. The ADSL connection couldn't be established anymore.
While I think it was rather a hard disk crash and not a direct smoothwall problem, it made me feel like replacing my smoothwall with ipcop, another firewall dedicated linux distro (forked from smoothwall).
I'm very happy with ipcop at the moment, it's a bit more "customizable" than smoothwall. I know both are GPL'ed so they can both be customized to fit any purpose, but as ipcop is a 100% community-based distro, it is a bit more designed to be tweaked than smoothwall.
█ ServerSea – Low Cost High Quality Hosting
█ Free Domain
, 99.9% Uptime, Super Fast Servers, Backups, True 24/7 Support
█ Money Back Guarantee, Special Discounts