My experience with the gazelle was very similar to that of rorschachwalter. the keyboard is indeed very bad (mine was loose in the lower right corner). more annoyingly, when i first contacted them about the loose keyboard they did not tell me it was a common problem, they simply told me the way to take the keyboard off but no way to fix the problem. i later contacted them about it again and then they suggested to put notecards under the keyboard. while this worked, it is a somewhat ridiculous way of solving the problem.
what also annoyed me was that after one week i heard the first loose screw moving around inside the laptop. after opening the laptop, I noticed that 50% of the screws inside the laptop were not tightened properly. if you mind opening your laptop and your keyboard and fixing things, don't get this laptop.
i also had trouble with the microphone and skype only shows me a green screen on video calls. the lenovo of my wife with the same ubuntu version did not have that problem. i did not have time to fix this problem but given that on the same ubuntu version skype works fine on the lenovo and not fine on the system76 suggests that skype has trouble with some element of the system76 laptop.
further, if you plan to carry the laptop around you will notice that the edge between keyboard and trackpad starts touching the screen. that leaves a nice grey mark on the screen - great, that is exactly what you want with a glossy screen. i fixed it by attaching several 3M Bumpons along the top of the screen to keep the screen from touching the laptop. again, if you expect to buy a laptop, start running it and have no problems, don't bother with system76.
the laptop indeed becomes very hot, especially in the area where you palm rests. i don't mind, but i can imagine that many people will find it annoying.
i tried some gaming on the laptop. uru (game from around 2006) worked fine on highest settings in wine. the ventilation went to full power for it though, so it seemed as if i was playing at an airport. i have not yet tried any steam games which may be the real test.
i noticed that the screen switch button (fn+f7) did not work. that was right at the moment i wanted to start a presentation, great!
to nerdcommander: i would recommend to get a lenovo and install ubuntu on it by yourself. the lenovo of my wife which came with win7 and still gave much less trouble running ubuntu 13.04 than the system76 laptop. sound, video, function keys, fingerprint reader, etc. worked without any problems and their laptops seem to be build out of much better material.