The release of WindowBlinds 6 represents the coming of age of Windows Vista skinning. Certainly Windows XP users get a lot of benefits from WindowBlinds 6 but as pointed out in "Playing with Magic", a world without WindowBlinds 6 is a world in which Windows Vista customization is extremely limited.

I am always amazed when I hear someone say "Why would anyone want to skin their computers?" as they adjust their custom cell phone case. People trick their rides in every way shape and form. We're stuck in front of computers all day so it's not surprising that people would want to personalize it.
As I type this, only around 10% of the PC market has migrated to Windows Vista. But on WinCustomize.com, it's over 22%. So far this month, around 700,000 unique Windows Vista users have come to WinCustomize.com to download skins, themes, wallpapers, etc. A year from now, it'll probably be mostly Windows Vista users.
What's ironic is that Windows Vista is a better platform to customize because it's got many small buglets that were in Windows XP cleaned up. But it's a harder platform to customize because of the demands it makes on skinners. Everything from 256x256 sized icons (which are practically clipart unto themselves) to the differences in the myriad of editions of Windows Vista (Basic vs. Home Premium vs. Ultimate) combine to make Windows Vista a challenge for skinners.
If you're still running Windows XP and you're happy with it, then stick with it. The amount of cool stuff for Windows XP continues to grow. But if you're a Windows Vista user, the good news is, the future looks bright. In the coming months, you will see more and more easy to use tools released that will let you customize your OS in ways that are breathtaking.