Summary: These lenses are advertised as "L" type lenses and they are not. E-Bay should discourage false advertising, because every one of these lenses is being advertised as an "L" type lens and none of them are.
Summary: This lens is one of the best I ever owned. I create master portraits with this. See the example I have uploaded. This lens is good for events as well. The wide angle enables you to do close courtiers shooting.
Conclusion: I chose this over both 17-40 and 16-35 because I wanted some leeway above the f/4 aperture of the former and the latter (mk I version) was $300 more. So I found a guy who was selling a very decent copy of this lens and... it's been with me for over 1.5 years.
Pros: + great build; + fast AF; + good sharpness, at least from about f/4.0 but usable wide open as well.
Cons: None really. I wish it had been sharp at f/2.8 but for the price, I can't complain.
Summary: its great, if you can get a good deal on one... buy it it'll be worth it. its an L lens, LUXURY. it might be a discontinued model but it still has great image quality. wide open its sharp in the center but softens around the corners, there is also strong vignetting shot wide open.