I am typing this on a Samsung Series 9 (900X3C) with Ubuntu and it is pretty good.
All drivers were preinstalled and it is a fantastic looking device.
I had to fiddle to get a few of the fn keys working however other than that, it is fine. There is an issue with the battery status which is a bug with acpi (https://bugs.launchpad.net/ubuntu/+source/acpi/+bug/971061). However I would highly recommend this combo and the Ubuntu wiki really helped (https://help.ubuntu.com/community/SamsungSeries9).
I have a 15" Series 9 which I use Unity on and it works great. I self upgraded to 16G and 256G. Complaints are minor - the keys are a little "rattly", and after about a year the CPU fan has a loud click when it starts up, which goes away after 30 seconds or so - something I only notice because it's an otherwise completely silent system (I'm guessing there's some dust in the fan). If they'd ever release the higher-res 2560x1440 version they showed off last year I'd buy it.
