Cory Doctorow has written a nice essay commemorating the 5th year of running ThinkPads with various Ubuntu releases on them.
My ThinkPad switch was inspired by a desire to try out the Ubuntu flavour of GNU/Linux, which I'd heard great things about. So I downloaded the latest version of Ubuntu – Canonical, the company that oversees Ubuntu, does two releases per year – burned it to a CD and stuck it in the computer, and, a few minutes later, I was up and running. At the time, I promised to document my joys and frustrations with GNU/Linux, but a few months later, once I'd been soaking in the OS for a while, I went back over my notes and discovered that there was practically nothing to report on that score.
My own Ubuntu experience has been very similar. I'm on my third year of running Ubuntu on various machines, and it's been vastly easier and more straightforward than I had expected. I'm not such a big fan of the new "Unity" window manager, so I still use "Ubuntu Classic" but that's just a little whine about what has been, overall, a very successful experience.