While they have plenty of limitations, tag clouds are excellent for outlining the relative importance of many concepts at once. They're also visually very attractive, a lot more eye-catching than a uniform paragraph of text or a bullet-point list.
I'm having trouble coming up with any arguments on what a 3D tag cloud is actually good for (if pushed I'd mumble something about using the extra dimension to show time information) but boy, is it it pretty! Awesome job by Roy Tanck, and thanks to Logic Nest for finding it.
I really like the 3d tag cloud but it makes it a little harder to notice certain words. With a normal tag cloud, the tags jump out at you because they are all there. With the 3d tag cloud you have to rotate them around to see them all. Then you have some hidden behind others.