At first I was like sure many before deciding with or without IS, but if you have when you can adjust the ISO up is not a problem a good DLSR, which are not absolutely essential, because anyway as much light is captured. I have the IS at the EOS 600D does not miss and the 5D Mk III certainly not. Clear As it gets darker you would need probably already one but I use this lens anyway only a day and then there is no need to pay extra even a 1000 plan.
What surprised me is still the focus. They say that prime lenses are sharper than zoom but in this Tele I add this statement in question. Actually, I would say that the 70-200 is to be equated with a fixed focal length, at least in terms of sharpness.
Vignetting, chromatic aberration or distortion are so slight that they are barely visible.
Bottom line, I would recommend to anyone this lens! Actually, it's a must to own this lens.