Reason being it has heaps going for it

*Heaps of addons
*Bandwidth limiter
*It's Free
*Wireless Traffic Control via MAC and IP ADDY
*Content filtering
*Snort intrusion detection on all interfaces
*It's free
*Eay to setup
*makes use of old hardware
*Is also a transparent proxy
*Veeeeeeery Fast! even on old hardware

Keeps me happy