Originally Posted by PaperPrincess

You get accurate, repetitive cuts. So for instance, all your 2.5" strips are 2.5" every time. You don't get that 'ruler nudge' error.
If you do applique, you can iron the fusible onto your fabric, then cut a shape. Again, same shape every time. As you get more used to the equipment, your cutting speed will also increase.
Look here for more info:
http://www.youtube.com/watch?v=X3ka4EcSsrk
Some folks complain that it wastes fabric, but I don't get any more waste than with a rotary cutter. Not sure what they are doing...