I'm in the camp that says that's it not a great product - but it's certainly a LOT better than no firewall at all. It does have an elegant simplicity.. and as has been said, if you go onto the internet without it you'll be 0wned in 20 minutes or so.

Personally I use ZoneAlarm (the one with the integrated AV is pretty good) but the firewall on router keeps the nasties out anyway.. so really, ZoneAlarm is there to mitigate against attacks on the wireless LAN somewhere and to provide egress filtering. But you know, for 99% of users that's probably overkill.. but for power users it can be extremely useful having that sort of granular level of control for inbound and outbound network connections.

I'd sooner spend $60 a year on a decent package like the ZoneAlarm Internet Security Suite which gives you pretty much everything you need rather than take the risk.