It's not just the standing that helps-it's the ability to switch back and forth easily. Before this desk, I could feel my back start to tighten up after about 3/4 of my work day. Now when I feel a twinge of a backache, I switch to a standing position and things feel much better. Another underrated benefit of the desk is the ability to change its height while I'm sitting. In the cases when I either lean lower and sit straighter than usual, this desk allows me to move the monitor to eye level without much effort, thus preventing neck aches.
One problem with the steelcase, however, is that it doesn't go high enough. I have a colleague that is 6'2" and he finds that the standing height of the desk is too low for his tastes. I'm shorter than he is, so this isn't as big of a problem for me. Now if only I could afford to buy one of these for home.....
edited: clarity