Pros: Comfort, build quality
I had to use these at work for a while (which meant putting away my DT990 in a drawer).
Immediately I was impressed by the build quality, the weight of them instilled a high level of confidence.
On the head, they felt comfortable considering the heavy weight, but the clamping pressure was slightly too high. Not deal-breakingly so however.
Then I plugged them in and proceeded with various listening (music, video (youtube) and gaming).
At music they were just awful. Almost no redeeming qualities.
Video has a strange spacial quality to the sound that was rather distracting. Even after playing around with the 5.1/stereo settings it always sounded strange.
Treble was like mushy tin foil: Especially the 'rear' drivers sounded like the headphones you get on a plane.
Mid range was recessed, thin and lower resolution than a Koss PortaPro.
Bass was somewhat acceptable. There was no 'boom' or significant bleed into the mids and the extension was pleasing. Perhaps this was the only redeeming feature.
5.1 directionality for gaming was marginally better than my DT990, but with the reduced sound quality I absolutely couldn't stand gaming with these, as the sound quality/timbre changed drastically as sound moved from the front to rear speakers which was annoying to say the least.
This is an older headest, but I hope to prevent someone from thinking they're getting a good deal if they see these cheap for 2nd hand, thereby making the world a slightly better place for someone somewhere.