You can use a simple configuration on your local network, without the need for proxy daemons. The firewall itself is also a straightforward machine, with a minimum of processes running. The Linux kernel used in this firewall, 1.3.68, is relatively new. It will have to prove itself in the long run, but it looks promising. The hardest part of building a good firewall lies in building good packet rules.
Careful analysis is important to building good rules, but the ultimate proof is thorough testing.
Test these rules, test them again, and then test them some more. One good test strategy is to probe your firewall using Satan running on some Internet host. I cannot stress this enough, the heart of your security lies in the rules you specify for your firewall. The rules given here work for me, but that doesn't mean they'll give you a secure installation. I would never presume that they are completely watertight.