People who check out this lens need no introduction about the lens. Its one of the best lenses from Canon stable. Absolutely awesome. This is a macro lens with 1:1 magnification. Maximum aperture being f2.8. Has a 4 stop IS. I bought this lens after comparing it with the non L lens. In terms of sharpness this lens is as good as the non L if not better. The AF is definitely faster compared to the non L. Silky smooth focussing. Beauty of a lens. Sharpness is pretty good. Color rendition & contrast are very nice. Excellent IQ. The autofocus is something that blew me away. Stunningly fast. The lens does not extend during focussing unlike couple of other third party lenses. There is a focussing limiter switch that helps you to choose the range within which u r focussing. 0.3 to 0.5 meters, 0.5 to 1 & >1m. This helps the focussing to be faster. Bokeh is nice. But not the best in the class. The 180mm lens has much better bokeh. However it still produces lovely bokehs. The body is not made of aluminium but kind of high quality plastic. Feels light for its size. Good balance when u hold the lens in ur hands. The IS is superb.Indeed 4 stop IS. Even a hand held shot at 1/60 gives u pictures with decent sharpness without blur. If you want to consider the lens only for macro photography the the non L is good enuf. if you want to take some hand held shots & attempt some portrait shots (though I wud recommend the 100mm f2) then the IS really helps. There is a bit of fringing & a bit of CA at f2.8 but only mild. The lens hood is textured. Compared to my 70-200 mm f4 L IS USM, the sound when IS kicks in is not present. Its very quiet.

Bought this lens off another site. I'm professional jewellery/portrait photographer and this lens by far exceeds all expectation. Tack sharp pictures even in low light, absolutely to chromatic aberrations or vignetting! Sharpness is maintained right from f2.8 till f16 and then it starts dropping slightly.Built like a tank but auto focus works like hot knife on butter, smooth and silent. Full time manual focus is of great advantage while shooting in low light.