The plus points: Highly detailed, energetic sound. The most detailed I have yet heard (after a long trail of cans including AKG 701, AKG 'open' ear speakers, Beyer electrostatic, now discontinued, Stax electrostatic, Beyer 770 and 990, Koss, various Sennheisers and so on. Good soundstage, exceptionally so for a closed back design. Quirky retro design.
The minus points: Coloured, boxy, biscuity tonal character, over forward upper midrange and treble, uncomfortable to wear, headband too large/ or to put in another way, not enough scope to reduce the range of adjustment, very sensitive to position, over dry bass, dynamics lacked shading - too forward all the time.
So it was sent back to Amazon; if you can't get the cans to fit there isn't much point. I think Beyer are really on to something interesting that with refinement could be truly amazing. But as a first generation product it is way too uneven. If your taste is for edge of the seat, crisp reproduction, and you have a big enough head, these should be auditioned.