Its all about be used to it, its no longer hard to do
I've been using Ubuntu for nearly 4 years since the 6.10 release and then full forward since 7.04-7.10. Ubuntu has come along way from there, having to regularly input screen settings, wifi driver issues, laptop fn key problems, etc the list goes on. All I can say is ubuntu and linux in general has done more for their os in the past 4 years then since Microsoft released xp for windows. Ubuntu is no longer hard to use, it just works in a different way to windows, sure I still do things using terminal but thats because when installing software its quicker than loading up the ubuntu software centre and the same goes for other tasks. What it really is, is that people are used to windows and it does things in a different way and as soon as you have to do something slightly differently, that is interpreted as hard. Even quite a few windows programs will run in wine, alot of newer programs such as spotify and picasa are designed to be able to run with wine, so they can quickly make a program for both systems without the need to cross-platform. Ubuntu 10.04 is a winner.
To the person commenting on a 6 year old using it, yes her needs are simple, but at the same time most peoples needs are simple, the don't need games or specific windows programs, with most things being internet based what he was trying to explain is that a 6year old can use it for the same tasks as say a 20-40 year old would be using it for.