I got started with Linux in 1994 and have been using it ever since. I use WindowMaker for my desktop environment since it manages to be both ultra fast, yet beautiful looking.
From a computer hobbiest's perspective, the thing that makes Linux so exciting is how it manages to put the "fun" back in computing. The average Linux user is passionate about Linux! On the other hand, MS Windows is a system that inspires little passion among it's users-- it's a mostly functional, boring system, comprised of many questionable design decisions.
From a knowledgable IT professional's perspective, Linux puts the "simplicity" back in computing. Linux makes servers seem simple and straightforward. With Linux the system administrator can acutally understand how the system works-- an invaluable skill for troubleshooting problems. By comparison, Windows is like a very complex "black box" that is often impossible to fully understand. Microsofties like to brag about the complexity and sophisticaion of Windows, but my experience tells me that complexity is generally something to be avoided, not embraced. The KISS principle (Keep It Simple Stupid), is sound advice.