Excerpt: I shoot primarily high school sports and rely heavily on my 85mm f1.8 lens for indoor events, as the lighting in high school gyms, field houses, and pools is iffy. I bought the 100 f2.0 to extend my reach and still manage high speeds in low light.
Conclusion: Well,....if it weren't for the CA,...this lens would be pretty nice to work with.. It was noticeably not as sharp as my 85mm f1.8 either.. The CA was noticeable up to f4.0..and wide open, it was so noticeable that it made shooting wide open unacceptable.
Pros: Nice focal length for portraits / head shots.. Fast, smooth AF.. Build quality is good..
Cons: Useless wide open..because of the CA.. Not as sharp as 85 f1.8
Conclusion: I purchased this lens and a EF 50mm F1.4 based on the reviews here. I was looking for a good quality, fast, medium telephoto lens for my 20D body. The build quality of the 100mm if much better than the 50mm F1.4, but I cannot recommend it with a crop digital body.
Pros: Small size and light weight, solid build, excellent from F5.6 on
Cons: CA and lack of sharpness below F5.6 on EOS 20D