I've been running Vista x64 for a while now, from beta versions to the final RTM, and I have to say I'm really happy with it.
When I installed builds prior to RC1 the bootloader had an annoying habit of 'losing' the Vista startup files, prompting a repair every 3rd or 4th boot, but this was fixed with RC2 and since then I have to say I've never looked back.
My only gripe is with manufacturers, who seem to have been caught on the hop with the need to provide 64-bit driver support. As much as some might like to, we can't blame Microsoft for this. 64-bit Windows has been available to the public since April 2005 and the SDK's were available way before that. Even so, it seems that quite a few manufacturers misjudged the demand for x64 drivers and thought that concentrating on x86 drivers would get them through the worst - despite MS making it clear that in order to gain Vista WHQL certification they would need to provide both x86
and x64 versions of drivers with their hardware.
Anyhoo, I have only one device which doesn't yet have a signed driver, and having disabled driver signature checking on boot I have no problem running the temp driver until a proper one comes out.
Would I go back to XP? No - but I have kept it on a separate drive just in case. After all - you never know when the DRM badness might kick in and start doing silly things like revoking drivers because MS decided that it was in their best interests to do so.
Other than that, I'm really happy with Vista and the few annoyances I have experienced were nothing more serious than the problems I had when I first upgraded to XP; in fact, most of them were almost exactly the same problems, including trying to find a modem driver that would work under the new OS, and using a driver from the previous OS to get by until a proper Vista version appears.
