The result of this is that things are much snappier. How much snappier? I timed a few things of importance to me, booting my laptop and virtual machines, starting delphi and rebuilding a medium sized project (600,000 loc).
Overall, using an ssd cut the times by an average of 39%. Not too bad an improvement. To put it another way, my "getting started" time (boot laptop, boot vm, start delphi) went from 6:05 to 3:37.

Edit:
The Delphi 2007 install is screwed up somewhere. It certainly never used to take 3 minutes to start up:( but sometime last year it started getting really slow. I don't use that install or vm much so I haven't bothered trying to sort it out.