I've been using Ubuntu as my main desktop (at home) for the last 6 months and I need to say, I love it!, here are the reasons why I love it:
Easy to install (well almost easy to install).
For the most part the installation process is very straightforward, just get a CD, put it in your laptop/desktop cdrom drive, select install and click next until it is done! Now, there are occasions where your hardware may not be supported out of the box, if this happens, you have 2 options:
Try to fix the problem, don't even try this option if you don't consider yourself an advanced computer user.
If you just want to see if Ubuntu will work on your computer, try the live CD, if everything works, then go for it, if it doesn't, I'll recommend you to wait.
Tons of applications.
There are a lot of open source applications for Ubuntu, which are easy to install by using the Add/Remove application, just run the application, select what you want to install and you are ready to go!
Bring back to life old computers and low cost computers
I installed Ubuntu in an Acer 5315-2153 which is a very low spec laptop (vista crawled on it) but with Ubuntu is a snappy laptop with a lot of computer power. The only warning is that the wifi and sound are not supported out of the box and it took me at least 4 hours to make them work.
In my next post I'll write my experience connecting my Palm Centro with my Ubuntu Laptop.