I have the first version of this lens and am very happy with it. One knock I've seen commented on about the mkII is the bokeh is a bit more 'nervous' as compared to the first version. Not to say it's bad, but just not as 'creamy' as the original version. Aside from the cost to upgrade, this one quality is of concern to me in contemplating an upgrade. Can anyone comment on this comparison, is it fair to say the mkII isn't quite as nice in this one respect as compared to the original 70-200/2.8 IS?
I owned version I of the lens...when I saw the sharpness of the II version...I gulped at the price...but made the leap, selling my version I to help finance my lens mania, LOL. Every time I shoot with the lens I now get to gulp at the images...the sharpness ALWAYS wows me! Every time. ...but yes as usual in photography...it comes with a trade off..the bokeh is more "nervous"...but for me the sharpness is so astounding thru the zoom range that I accept the trade off.
If I really need to get serious about bokeh I pick up my 85mm f/1.2...and I am considering picking up a 135mm f/2.0 so that I can have fast AF AND creamy backgrounds when needed, as the 85L does not lend itself to fast AF....Seems that you just cannot have it all!!!