I started playing with OpenBSD 6.3 as a desktop (actually laptop) OS a couple of months ago. Installation was very straightforward. In my case I used the whole disk, no dual boot.
Here's a tribute/introduction written by Derek Sivers:
As for my own experience, I don't know if I'm ready to give up Debian as my primary desktop OS, but I really like OpenBSD on my coding-or-surfing-on-the-couch laptop.
On the server side, I also use both (as VPS) for personal projects.