Just thought I'd show this here too (I've posted this in another thread dealing with Vader) since Mquin's video review was a contributing factor to me finally buying the Rubies Supreme Vader costume.
It's displayed on a mannequin and stands at 6'8''. I wasn't happy with how it looked just thrown on the mannequin at first (He looked way too scrawny and the suit looked baggy as hell) so I padded it up with bubblewrap to try and give it a more muscular Prowse-esque physique, and I think it was a big improvement.
I do plan to modify the suit eventually (scouring the 'net and these boards for tutorials on repainting and lense modification), possibly into the ESB version; but for now I'm quite happy with the display. I know its not super movie accurate, but positioned right, with the proper proportions, I think it can look damn near close (from a distance haha).