Pros: Build quality, high resolution, balanced tone, great extension, wonderful bass, stellar comfort
Cons: Mids a bit recessed (with standard pads), highs slightly too strong, spaciousness not brilliant (with standard pads)
Great headphones with well recorded music.
With modern recordings mixed with plenty of high frequencies it just pierce your eardrum, but perfect with Chesky and similar well made recordings.
My trick to make them sound wonderful is reversing the pads, it is a bit uncomfortable (the hard part of the pad is on your skull) but the gain is so big that I am happy like this. (I couldn't find any suitable pads that gives the same mid/spaciousness effect.
UPDATE: I found the AKG k240 pads + some foam on the frontal part of the pads to be perfect with these headphones, now with some burn in and the new pads I found the bass amazingly tight and bottomless, the mids are not recessed anymore, also with the new pads more punch was obtained. The spaciouness is now far beyond any closed cans I ever tried (even more than the AKG K550) and many other open headphones. I can't believe that a closed can could deliver such a spaciouness and soundstage and still preserving the good aspects of a closed can. At beyer they must have used some hybrid technology (see the lateral port on the caps) even though because the isolation is not perfect.
I have to say that the new pads didn't fix the highs which are still a tiny bit too pronounced on some recordings for my taste, this can be tiring especially listening to female singers for a long time, however I also found that with some well recorded acoustic music (jazz and baroque without tons of post processing) the high frequencies are amazingly pleasant and revealing, adding that "real" sensation to my ear.
I think these headphones with this configuration (AKG pads) are perfect for professional studio recording, they are an extremely revealing and balanced, crystal clear, high resolution machine, well done Beyerdynamic.
Please notice that I am also firmly convinced that talking about things like the amplitude of the different frequency sections is a very personal evaluation, since this aspect is strictly associated to a large extent to the shape of the ear canal of a specific subject and to a less extent to the shape of the pinna, without mention the psychoacoustic response of the brain. However it does exist something like the "average" listener which has an "average" frequency response perception, but statistically there will always be many people outside this average range that will hear things differently, especially in terms of frequency amplitude perception in the high frequency range. A more "scientific" evaluation should be done between parametrically equalised headphones using open ear canal probes and good linear near field loudspeakers.
P.S. These cans are also by far the most easy to drive headphones I ever tried, altough they still benefit of a good amplicifation in terms of clarity, resolution and vividness of the bass section.