9 out of 10 points and recommendedSharpness, vignettingNo weather sealing
This is one of my all time favourites. Already wide open this lens produce some high quality photos. Sharpness, contrast and the natural vignetting on full-frame cameras is awesome! Some people may disagree with the vignetting being a good thing or not, but thats a matter of taste I guess.reviewed February 4th, 2010 (purchased for $1,625)
I have found myself shooting wide open almost all the time. Because it manage to do so. Yes, there is some sharpness added when stopping down to f4 or f5.6 but after that it doesn't get better. This leaves you with a buttery bokeh and an object in perfect focus.
On FF I use this lens for both tight portraits and landscape shots. Its a joy to work with every time.
Only con I can think of, and that may be a big one depending on how you plan to use the lens is the lack of weather sealing. No rubber sealing against the camera body tend to give me the creeps when shooting in the wet. Perhaps it's not a big thing, but for a L-graded lens this feature should be expected.
9 out of 10 points and recommendedf1.2!expensive
A tank! WOW what a feeling it is to just hold this lens in your hands. Its bulky and heavy for its rather small body. It feels and works smooth and exact.reviewed February 4th, 2010 (purchased for $1,420)
Some may argue about the image quality at f1.2 but hey, for my eyes and how I use my images (not printing larger than A3) it is perfect. I have shot complete photo shoots at f1.2 with great results!
It can be really hard though to hit the target, since the dof is really short wide open. But the benefit of being able to shoot in really dim light without the must of a separate flash is so worth it. There is some vignetting for sure but I love it. If there is not enough I always add some in PS4 ;)
Weather sealing making it a perfect lens even when the weather is crappy. Full time manual override focus is great, even though its really hard to hit focus manually when shooting f1.2
If you dont tend to use a lens at wide open or don't need that extra step you can easily choose from Canons far cheaper lenses at 1.4 or 1.8. But as they say, there is no substitute for a large aperture but a larger aperture... so true. Try it, and you'll love it!