Hello, I've done it.
It's useful - the complication of NAT is removed, and it's good for thinking about how ip networks work.
I use sixxs.net as a tunnelbroker, and just configured my router (cisco 837) to use this tunnel. The router is also set up to advertise the ipv6 subnet and all hosts on the network automatically pick up an address.
I've had more problems in Vista than XP to be honest. Once the ipv6 driver is installed, it worked pretty well. Vista seems to have real difficulty in doing ipv6 dns lookups however, which I can't find a good answer to. For example, some of the time, I can access ipv6 sites and my mailserver using just the ip address, but using the dns name fails. Sometimes this is fixed by a reboot, but will be broken next time. So my advice would be to steer clear of vista for the moment.