Depends entirely on the circumstances. The larger companies have access to virtualisation technology to test compatibility before large scale rollouts/upgrades, and for smaller people, it doesnt hurt to make a small partition for testing purposes on a spare box to see how it goes.
I'm not having any other real issues, at least none that would stop me upgrading to Vista.
Most the problems that Vista is having is really "targeted" to home users - there's not a great deal for office workstations that's gonna bother a vista pc. Unless the user is streaming media and copying files over networks
