At open aperture, in particular towards 200mm towards the 70-200 / 2.8 was not as sharp, and a waste moreover towards corners. Which of course is particularly striking at a full frame camera.
For 70-200 / 2.8 IS II: apart from the fact how much better it is already at full aperture (and why I buy the Trumm, if I do not use the 2.8?) That I ca 80% use, the Image Stabilizer does the rest.
There succeed at 1 / 30s 2 of 3 pictures, provided that the object (usually a subject, so man ..) does not move, it would be unthinkable without stabilizer.
Even at full aperture excellent sharpness and contrast, the corners are very good at stopping down they are as excellent as the center.
Autofocus: because I do not have measuring equipment, I can just hold on, it's just as fast as my old zoom, and that was very fast. Apart from this, you can limit the range of distance, which makes things a little snappier.
A Trumm, hard (Stativschelle is a matter of course), but the results are worth it.
And expensive. But who buys that has (currently!) The certainty that it is the maximum of the currently feasible.
So who can afford sichs: RECOMMENDATION!
PS: the bokeh is not really better than the old, and certainly not as the the 135 / 2.0L, but a tiny advantage have fixed focal lengths but still have .... And that favor / do not like is a deeply subjective matter )
Edit 15/02/2012: after over a year of intensive use my favorite lens (from now 8).
It is the combination of sharpness, the image stabilizer which allows recordings that were not possible without (driving car at night, 1 / 30s, and a slight Mitzieher- looks great!).
The other optics are struggling against this, the flexibility and quality are unique.
Since I very often use the 1D Mk4: the autofocus is very fast camera adequacy is built for speed.