Simple. It works well for what most users do.
- The UI in WinXP is very inconsistent and horrible once you're used to a more consistent UI. There's not much debate here, WinXP is hardly the epitomy of fine UI design except maybe for the most rabid Microsofties.
- No virus, no spyware.
- Full command-line power with easy to use GUI. Try this with Linux or Windows. Keep a link to a file on your desktop, now drop down to the command line and rename the original file. Used to break Linux, it might try to search now, Windows will try a search if it's similar. OS/2 has no such problem, the 2 are automagically linked.
- A real GUI for the OS. Come on, Linux is very pretty (I use Ubuntu everyday at work), but there's a lot of inconsistencies and at heart, it's still basically a X-Window manager. You think it's great, but not after you've used a real GUI. (Dang I wish GNOME or KDE would _copy_ from some of the best GUI's).
- OS X is a possibility, but you have to buy Apple hardware only.
- It's not a resource hog. I can fit my OS and all my applications (Yes, including OpenOffice 2, GIMP and everything you need under the sun) in a couple of GB if you wanted to.

Let's face it, most people (and that would not be people in Slashdot) just check their e-mail, browse the web and write up the occasional document. OS/2 does that easily and simply. I have to use WinXP and Linux (and Solaris and HP-UX and...) at work, but I'll fully switch when Linux or someone else gets their act together. All the alpha-blended, draggy morphing windows in the world won't make a great UI if the _behaviour_ isn't there.

If you need to get an updated, currently supported, purchasable version of OS/2, you can use eComstation.