On balance I’m satisfied with Vista x64, but I’ve run into a few challenges and at least one casualty.
The casualty was my Palm Tungsten E2, which can’t connect to Vista64 with the USB cable. According to Palm, you can connect with Bluetooth, but I don’t have Bluetooth on the computer. Fortunately I don’t use the Palm much anymore and I synced mainly to back it up.
As for the challenges, it seems that some applications, notably OpenOffice.org 3, have to be installed using XP-SP2 compatibility mode. Also, some installation software doesn’t trigger privilege elevation which may be required to write to certain registry keys or system folders, so the “Run as Administrator” and “CMD prompt here as administrator” Elevation PowerToys are practically necessary. Sun’s Java RE (which I probably wouldn’t install except that it’s a dependency of OOo) has an annoying bug in its control panel such that you can’t change the settings, so you can’t disable automatic updating. The workaround is to run bin/javacpl.exe as administrator using the Elevation PowerToy. Using 32-bit Windows help files (.hlp) requires a special download (this affects all Vista versions) as Microsoft is no longer updating the older help program and so doesn’t distribute it with the OS. Only two of the four buttons on my Kensington Expert Trackball Mouse work, and Vista thinks it’s a regular mouse — but it wasn’t working fully under XP-SP3 either. Don’t bother to install the MouseWorks software, although some folks claim they’ve gotten it work (or at least the OS to use the driver). I would guess at this point Kensington isn’t going to release a Vista-compatible driver for the older devices.
I can live with two buttons.