I think that it offers a good handiness for geometrical figures. I've only seen that it was useful for basic figures...
In high school, we sometimes used it for geometrical traces (sort of locus...)
Anyone familiar with Geogebra? One of my coworkers came back from a conference raving about it. It looks good, but I've only had a bit of time to play with it.
If you have opinions, or if you find a use that's not immediately obvious, let me know.