Detailed transients, precise imaging. Needs EQ < 80 Hz and sounds great with it. I'd rate their sound with EQ 5 stars, without EQ 4 stars.
Earpads, pouch and case stink. Very handy to be able to disassemble the D1 to spray water/vinegar (1:1) on fabric parts. This abated the smell enough to enjoy music.
I hear some microphonics through the cable when I move around and I don't find it distracting. The y-split cable I find annoying to cope with: it can get stuck. Taking off D1 from around my shoulders is either a two hand activity or requires awkward movement. My preference would have been a connector on either end that accepts the signal for both drivers.
I'm sensitive to clamp pressure (most headphones give me a headache within 10 minutes) and can wear the D1 for an hour. I've read one can bend its headband to provide more comfort and that this can affect the sound.