I have successfully used this product for several months now, both in backup and restore mode. Having bought a Vista PC I have used the software to backup the hard disk before tuning/tweaking Vista, and restoring back to the original install point, using the sector for sector image copy capability. I've also used it to backup my old PC disks onto a Toshiba 320GB USB drive, and restore onto the new PC's hard disk. These restores have successfully created new logical partitions on the target hard disk, using free space available.
The product that ships on CD needs a patch from the Acronis site to be Vista compatible.
Like somebody below, I had a failed install with the error message, but using Windows uninstaller in Control Panel got around that problem. I've also found that the boot CD isn't always reliable, with the result that you don't always have a mouse unless you boot into Acronis Safe Mode, which means that backups/restores run far more slowly. For those reasons, it doesn't get 5 stars.