Sorry, I shall not get into CA and little inconveniences since they were not important enough to bother me.
I just wanted to say how amazing this zoom lens is for its overall qualities which convinced the jury to win the 2011-2012 EISA professional european lens award.
Compact enough to fit into a reporter's pocket, fast focus (humm… better using a 1D MkIV than a plagued 5D MkII), efficient stabilizer,very good to excellent IQ throughout the focal range (the fall-off beyond 200mm is not obvious), this lens does not fail to amaze me. Not dirt cheap but worth every penny, this is a clear winner.
When I go out with it, I unconsciously know and feel it's going to deliver and it does every time. I grew a fondness for this one and if I ever get tempted by another setup, like a coming 200-400mm, it is going to be a struggle to let go of it. On vacation or distant assignment, this is the compact gear you want. According to reviews out there, the new 2.8/70-200L II seems still above, but with animal photography, children and even ordinary portraits, I don't know if the latter's IQ preempts losing the extra usable range beyond 200mm, which on numerous occasions allowed me very good discreet portraits I would have missed with a 70-200 zoom.