Astonishing.... Build is top notch. Plastic, yes, but lighter than the old one and the balance is great on a body. AF and handling is as you would expect from a modern L. Optically it is jaw dropping. Wide open at 24mm, the corners have no right to be anywhere near this good. There is an improvement as you stop down but it is very minor. I did some basic tests to ensure that the lens is optically 'OK' and saw results that just beggared belief, when inspecting the fine twigs on strips of poplar trees or the leaves on hedges, gravel etc. All done to ensure a flat plane of course. I bought this 24-70 L II lens for commercial work on digital bodies, but it is going to get used on my Eos 3 and 1n HS bodies too. It is going to get a LOT of use. The lens is insanely expensive (but not compared to Leica of course) but is without question the best zoom lens I have ever used and far better than most primes. I will now sell the other mid range zooms which never quite made me happy. On my Eos 3 for general purpose documentary work with B&W film, this lens is going to be incredible to work with. FWIW I got mine from Hdewcameras in the UK and saved a small fortune over the likes of warehouseexpress. About £500 in fact. Yes, a lot of people have complained that this lens is much more expensive than the MK I version, but I'm seeing a level of optical quality I have never seen before in a zoom and which would leave me delighted in a premium branded prime. I am quite confident that shots from this lens will stand up quite easily to those from my Zeiss and Leica primes, save for a split hair or two. No, I have not done any direct comparisons, but aside from distortion (where the zoom loses hands down), there just isn't any need. Performance is way beyond anything I am going to see resolved with the films I regularly use.