I tried installing OpenBSD 5.6 with XFCE on a Thinkpad X300, and I didn't have any trouble with the hardware I use, or the base system, in fact everything looks well though out and documented in the manpages. (Gnome works too but it feels quite slow even on Linux)

In the end I switched back to Linux when I encountered trouble with applications from the ports, for example libreoffice dumping core everytime you click somewhere in a spreadsheet. I did write down all the tweaks/configuration that I've done on the system in an ansible script, and my plan is to try again with the next release, and report some bugs if it still fails.