On a related note, I just got this lens and didn't expect it to be so tiny. Mounted on a 50D I can barely put my left hand under it and I'm struggling to find a good balance to hold the camera properly.
Had the same problem, sold my nifty fifty off after a months use and picked up the Sigma 50 f/1.4. Now I have drastic difference in balance and Manual Focusing.
For the OP, no it is a waste of money. Unless you are buying it to make the fifty look bigger I wouldn't get one. As people have mentioned it rarely flares and it isn't really that expensive so in case you shatter the front element it would just be cheaper to pick up another one. On another note I loved how little and easy it was to transport. Could bring it in the pocket whilst on a photowalk.
Hell the guy whom bought mine was asking why there was no filter included, I tried to tell him that if he wanted one of my filters he had to cough up another 50 bucks.











