I bought it at the same time I bought my Crescendo last summer. Out of all the "extras" I have purchased over the years (and that is a lot), it was the best purchase by a mile. I love it.
You can program what functions you want the small side pedal to do. I have the bottom of the pedal set to cut thread. I have the top of the pedal set to raise/lower needle. I have it set up with the small pedal to the right of the regular pedal. That way, I can work my foot/leg to the right as I finish sewing, move my foot to the right to hit the thread cutter then raise my leg up to the right to raise the foot with my leg bar.
After a very short time, the movement became very natural feeling and is second nature. Love it!!!