I have this lens for two weeks now, was able to make some test and wow, pictures are so sharp, it reveals the real and full potential of the CMOS sensor on my EOS 20D, even my 10D!
Before making some test, I was thinking of changing my 1.4x and 2x extenders, but after looking to the shots I made with those two old extenders, I don't think I'll need de new II versions!
Focus is very fast, accurate and the sharpness in incredible!!!
Chromatic abberation with this lens? What chromatic abberation? You're kidding...right?
Quality of construction is imppeccable, it is truly a remarquable and exeptionnal lens in any way.
Ok, it is a little bit heavy, but who cares? with a good monopod and little practice, you will eventualy forget about it.
Handling this baby will become a second nature and you will enjoy the full experience of working with it!