I extensively reviewed the Beta of Windows 7 for CPU Magazine.
Here's my executive summary:
I quad-boot my desktop computer. One of the OSes is a very clean installation of XP that I use solely for gaming. One of the others is XP with all the various bells and whistles needed for my hardware, my network, my work, and so forth. One of the others is Vista, which I mostly use for testing and troubleshooting. I would certainly reformat the Vista partition and put W7 on it. I would never touch the XPGaming partition and put W7 on it. If there was some program I needed to do my job that only came on W7, I would consider replacing my "work XP" install with it.
My main notebook came with Vista, which I promptly erased and replaced with XP. If my next notebook came with W7 pre-installed, I'm not sure I would bother replacing it with XP.
In general, I really couldn't find any advantage to using Vista over XP for most users. With W7 there are some tangible benefits over XP (and certainly Vista) that make it more equal.
-Llama