Regarding the 17-55 (which I own) and the discussion over quality, before I bought it my reading of the analysis and reports was that it was the optical equal of the L lenses, but that the build/quality control was not as good. Some people had issues with dust getting inside the lens, and some people had trouble with the image stabilization going awry prematurely; out of the warranty period, but still too soon.
This is the lens that lives on my 7D. Although I haven't had any of the issues, I would agree with the reports; it doesn't feel cheap or fragile, but it isn't as substantial as any L I've ever handled, either. That being said, without considering the color of the stripe around the glass, I believe that it represents a fair value at its price. It is an optically superior lens, with some compromises made to market it at the price.
This is the lens that lives on my 7D. Although I haven't had any of the issues, I would agree with the reports; it doesn't feel cheap or fragile, but it isn't as substantial as any L I've ever handled, either. That being said, without considering the color of the stripe around the glass, I believe that it represents a fair value at its price. It is an optically superior lens, with some compromises made to market it at the price.