The best lens I own

This is the best lens I own (I also have a 28/1.8 and a 50/1.4 for my EOS system, a 15/4.5 Voigtlander and a medium format system), and probably the one I use most.
It's very fast for it's focal length, f/2, and the great thing is that its very sharp even wide open. I have no hesitation at all to use it wide open. The rendition of very fine detail is improved if you stop down to f/4, and there is also very slight vignetting wide open, but that's it. Stopping down beyond f/4 there is no further improvement in image quality. Bokeh is very smooth and creamy wide open, stopped down I'd call it "neutral".
Autofocus is extremely fast and quiet. It gets even faster if you use the focus range limiter.
The lens is fairly compact and not too heavy (around 750 grams), but it gets quite long when you attach the included lens hood. Using the lens hood is almost mandatory to avoid flare and damage, the front element is very large and exposed.
Handholding is no problem thanks to the reasonable size and focal length, and the speed of the lens.
The lens takes Canon teleconverters, but I don't own one.
Build quality is excellent, it feels very solid, clearly better than my other Canon lenses. Manual focus is well damped, almost as good as an mf-only lens.

If you want a fast, sharp tele lens: look no further!