A good program to molest sound with. Not much needs to be said. Its very affordable, even without the student discount, it sounds great and provides cheap access to convolution reverbs - Of course you need to learn how to do it, but thats just like any other effect.
I would suggest buying this plugin to anyone with a mind to construct soundscapes. I would suggest this plugin to anyone who is making the more esoteric forms of electronica (Aphex Twin, Autechre, Boards of Canada, Plaid, Black Dog etc..) Although I am sure that its applicable in so many other forms of music.