I began playing with OpenBSD with the 3.2 release. I remember that as being a great milestone: PF was just starting to gain power and ALTQ, still a separated feature, catched my curiosity. I was deploying a wifi network to share Inet access in my town, so I looked for security, simplicity and a queue manager. That was love at first sight, a really K.I.S.S. solution for all my problems!!!
Whenever stuck with any problem I found the community to be very helpful, only to punish those too lazy to even look at the archives.
I never looked back. Now I keep several production firewalls, web and mail servers on OpenBSD, and do even more exotic duties, like control a milk vending machine, where I kept the OBSD busy counting coins and controlling little nice and smelly pumps, controlled securely thanks to OpenSSH.
What makes OpenBSD so great for me is that it never feels like a toy, but a tool. It is solid and consistent, like a good beer.
By the way... Beers for all!