I like that we have many different options when it comes to computers, and I run three of the more popular Operating Systems: Microsoft Windows, Mac OS X and Ubuntu Linux (Mac OS X being the one with which I have the least experience). All are great and have their strong points.
There are a few things that I like about Ubuntu. It gives you a feeling of freedom. Developers all over the world are always maintaining free software to support the Linux OS. The Ubuntu team continually makes this software and its updates available and free. And while I am not %100 against proprietary software, Windows tries to convince people that their certified software is best (and in some cases it may be), but you usually spend a lot of money on it and can end up spending more on updated versions.
Another thing that Ubuntu users like to proclaim is that it is safer from virus attacks than Windows. This is true, but only because %90 of virus attacks are aimed at the Windows OS. This is the same reason that some prefer Mac OS to Windows.
In my opinion there are a few good reasons to use Ubuntu. If you want to be a software developer, Linux gives you a lot of freedom in this area. I also think that Ubuntu has the same potential as any other operating system: Web browsing, video editing, music listening, etc.
I like to compare eye-candy as well, although this isn't important to the functionality of an OS. Windows provides some fancy stuff with Vista, like a 3d desktop, but you have to pay extra for this. Ubuntu provides nice features like these for free.