Opened the sealed box - lens in hand - panic - manual focus DOES NOT WORK!
Later after phone call to Canon - agree to try it on camera body first and then decide if it needs to go back for repair. Back home - connected to my EOS 40D and - voila! - the lens comes to life. It appears that the manual focus actually uses the USM rather than a mechanical connection so the lens needs to be powered. Finally found an obscure reference in the instructions confirming this. I really feel that as this lens is different to the usual Canon lenses, then Canon should emphasise this in their documentation and inform their telephone support staff - ah well.
As to the lens performance - this one certainly sets the standard. Colour (chromatic) abberation is non existant, barrel and pincushion distortion undetectable, viginetting is nearly zero and the resolution probably exceeds the sensor resolution (10.1 Mpix) on the EOS40D (APS C sensor). Great for portraits but even better for isolating flowers from their background foliage. Very pleasing bokeh due to the circular apperture. All in all an excellent lens once you read the instructions carefully.