I was concerned purchasing this lens as some other people had said it was not sharp wide open and did not seem to perform well on a 20D.
I can honestly say that on a 20D it is razor sharp wide open. The DOF is so small at f2.0 that you have to be extremely careful about the focus point - if the eyes are in foucs then the nose is not!
The focus is quick and response but remember you get the best results on a 20D by using the centre focus point.
The color is neutral and accurate, for me this is not an issue.
I also find the focal length just right. I have used an 85mm and this was (on a 20D) a bit short for my needs.
Build quality is good but not L standard. The size was a surprise as the lens is compact and easy to walk around with.
My only grip with Canon is that there is no supplied hood for which they then charge an outrageous sum of money for - $60 AUD for a lens hood. Also with the proper hood attached the lens cap is difficult to get on and off - buy a center pinch cap. I use the 65EW hood and this works just fine and the cap is much easier to get on and off.
I only give 10 for something truely exceptional - this lens almost has that something special and it has become the lens I use 60% of the time out of a collection of six lenses.