Ubuntu is a very reasonable average joe OS. It is actually really crappy for gaming - when I was using Ubuntu at the Unity switch around 10.04, there were tons of absurd full screen and tearing bugs in games. Even now that most of that is fixed, Unity/compiz is still vastly outperformed by everything else when running full screen opengl apps. On Gnome / KDE I never encountered those.
I just played Euro Truck Simulator 2 in Ubuntu 13.04 this morning. With the latest update it runs very nice. Full screen, no tearing. It has less FPS than in Windows, but that's expected for this particular game. Using an empty Openbox desktop to run it made no difference, the performance issues are not because Unity, but because of the game engine. I'm only working in moving my savegame from Windows to Ubuntu.
On the other hand, Portal and Half Life 2 run PERFECT in Ubuntu. Just as fast and pretty if not faster than in Windows 7. I'm waiting for Portal 2, as that's one game I have not managed to finish in any platform yet. They also support virtual desktops, so I can ctrl-alt-arrow them away in an instant if my GF needs something from me.
I'd encourage you to try it again. I'm running Ubuntu 12.04 on my Dell XPS 13 (Sputnik Edition of course) - and I have no problems with playing Steam games.
I havn't really had any problems playing any game that works on *NIX so far - not that there's all that many.. but still.
I switched to Arch a long while ago. I also prefer the KDE app suite, systemd, and pacman. I still like where Ubuntu is going, but KDE just has feature density I like. I just put relatives on Opensuse because tumbleweed is really solid.
I value that Canonical can bring people to *nix, but I like my customization and a lot of the magic that KDE can pull off. Also, I love writing QML + C++, though with Ubuntu transitioning to be qt focused I could get that anywhere.
I hope this means, more than anything, the year of qt is 2014, because I'd really like to get employed working in qml / qt projects.
