Ubuntu is definitely impressive stuff.
However, I have a laptop on my desk on which I can install Windows and it works, install Ubuntu and it won't. I'm guessing there is some hardware that is messing things up but I really don't have the time or inclination to find out. That means I would not use it yet on any machine I need to have working just incase I plug some hardware in that I want to use. If Ubuntu works it works very very well, but it's not quite there yet for me to put it on my mother's laptop.