I just purchased the same laptop. It's really excellent. But I am a little nervous about occasional panics when entering/exiting standby (15.04 vivid, 3.19.0-18).
I'm having a very good experience so far (14.04, 4.0 mainline kernel). Palm detection was broken, but the fix in [1] seems to have solved that as well.
[1] http://stevenkohlmeyer.com/fixing-palm-detect-ubuntu-14-04/