* Multimedia keys. They have the nasty stuck bug -see https://bugs.launchpad.net/ubuntu/+source/linux/+bug/271706. There are some partial workarounds -see http://ktemkin.com/en/?p=25, but none is totally satisfactory.
* There may or may not be an issue with battery life. I still have to see whether the life (just about 2 hours) is significantly longer with Windows.
* None of the fancy-pantsy stuff works, of course -no Eco Utility, no HDD protection that I am aware… But that is all minor.