Not a pain in the arse to install
Assuming your hardware is compatible it's a doddle to install. Stick in CD/floppy/netboot, tell it to use all the disk, partition (ok, so that bit is marginally harder than other osses but still not difficult) and answer some simple networking questions . I've had more problems installing Linux than OpenBSD, especially when Linux tries to do a clever graphical install that's not required.
It could possibly be seen as less friendly in use - there's not much cruft bundled like there is on Linux. However, it is very logical, the documentation is pretty good and the packaging system works - it just doesn't handhold you. Likewise mailing lists/IRC etc are reasonably friendly but it is very much expected you have read the documentation on the website and the manual pages first.