Customer Rating: 
Summary: Excellent for macro photography
Comment: Before making the decision to splash out on the Canon lens for my Canon EOS 400D (Rebel) I spent several months comparing reviews and opinions on various lenses. It came down to a choice between the Canon 100mm, the Sigma 105mm f/2.8 EX DG Macro and the Tamron 90mm f/2.8 Di Macro Lens. Each had its plus points but the general consensus of opinion consistently favoured the canon.
I do not regret my choice. For close-up work the 100mm lens is a considerable improvement over the standard 18-55mm lens, and for macro it is excellent. Best results are achieved when using full manual settings, and I find the lens performs at its best roughly between f8 and f22.
Using the lens as a standard telephoto I am not yet convinced, certainly when using it hand held. It is quite a heavy piece of equipment and I find camera shake a problem, but used with a tripod the results are good. But I am not too worried about this as it was primarily for macro photography that I wanted the lens, and on this basis I do not regret my choice.
Customer Rating:
Summary: Great value but slow to focus.
Comment: This is a wondferul lens with great sharpness and color. I have owned two over the years and have been very happy with them with the quality of construction and reliability. What makes me even happier is it is a great value since it can be purchased for less than $500 now. The only issue that I have is that due to its age, the lens is somewhat slow to focus compared to my newer lens. I would still recommend this as a great buy, regardless.
Customer Rating:
Summary: If only it were an L lens. I have to hide this one from my friends.
Comment: I like this focal length in a macro, and I like the aperture. I wish the L series macro were not 180mm, because I want a shorter macro. But Canon, those cads, don't make a short Macro in a L Series lens. So I had to buy some plastic. Oh well. It's fine, I guess. But not as sensual as my silky smooth L lenses. As a matter of fact, I am kind of embarrassed by it's lack of a red ring, and plasticky-ness. But it works ok, and someday, I pray Canon will make me a nice L Series, honest to god METAL macro in a shorter focal length. Like 65mm, and f2.5, OK Canon gods?
Customer Rating:
Summary: Fantastic!
Comment: If you are into photography and want to show detail then this is the lens for you. This lens is the best for showing great details in your photos. I photograph nature alot and this lens can even pick up the little white flys. If you want things that small this is the lens. When I photograph people it is awesome with closeup shots in showing how smooth or rough the face and hair are. I think this lens is the best lens Canon could have come out with.
Customer Rating:
Summary: Great Lens
Comment: This lens is amazing! Astonishing sharp and with a very nice bokeh.
Highly recommended!!!
Summary: Excellent for macro photography
Comment: Before making the decision to splash out on the Canon lens for my Canon EOS 400D (Rebel) I spent several months comparing reviews and opinions on various lenses. It came down to a choice between the Canon 100mm, the Sigma 105mm f/2.8 EX DG Macro and the Tamron 90mm f/2.8 Di Macro Lens. Each had its plus points but the general consensus of opinion consistently favoured the canon.
I do not regret my choice. For close-up work the 100mm lens is a considerable improvement over the standard 18-55mm lens, and for macro it is excellent. Best results are achieved when using full manual settings, and I find the lens performs at its best roughly between f8 and f22.
Using the lens as a standard telephoto I am not yet convinced, certainly when using it hand held. It is quite a heavy piece of equipment and I find camera shake a problem, but used with a tripod the results are good. But I am not too worried about this as it was primarily for macro photography that I wanted the lens, and on this basis I do not regret my choice.
Customer Rating:
Summary: Great value but slow to focus.
Comment: This is a wondferul lens with great sharpness and color. I have owned two over the years and have been very happy with them with the quality of construction and reliability. What makes me even happier is it is a great value since it can be purchased for less than $500 now. The only issue that I have is that due to its age, the lens is somewhat slow to focus compared to my newer lens. I would still recommend this as a great buy, regardless.
Customer Rating:
Summary: If only it were an L lens. I have to hide this one from my friends.
Comment: I like this focal length in a macro, and I like the aperture. I wish the L series macro were not 180mm, because I want a shorter macro. But Canon, those cads, don't make a short Macro in a L Series lens. So I had to buy some plastic. Oh well. It's fine, I guess. But not as sensual as my silky smooth L lenses. As a matter of fact, I am kind of embarrassed by it's lack of a red ring, and plasticky-ness. But it works ok, and someday, I pray Canon will make me a nice L Series, honest to god METAL macro in a shorter focal length. Like 65mm, and f2.5, OK Canon gods?
Customer Rating:
Summary: Fantastic!
Comment: If you are into photography and want to show detail then this is the lens for you. This lens is the best for showing great details in your photos. I photograph nature alot and this lens can even pick up the little white flys. If you want things that small this is the lens. When I photograph people it is awesome with closeup shots in showing how smooth or rough the face and hair are. I think this lens is the best lens Canon could have come out with.
Customer Rating:
Summary: Great Lens
Comment: This lens is amazing! Astonishing sharp and with a very nice bokeh.
Highly recommended!!!