Pros: Heavy duty construction, adjustable bass ports, stealthy looks, decent sound
Cons: Clamp, price
Out of the box, these guys are impressive. Killer looks, minimal packaging, obvious sturdy construction - in other words, German.
The sound was very good. They're easier to drive than most Beyer over-ears and they have a very good sound. I wouldn't say great. Coming out of my iPod Classic, the wider-than-average soundstage provided some excellent space for my live rock recordings. The bass was solid and got even better with my Fiio E5 - I imagine a heftier amp would do even better. The mids are so-so, not recessed in my ears but definitely not forward. The trebles were lacking, but they probably aren't supposed to be audiophile quality for the market these are targeted at anyway.
Overall I like the COPs, although the ~$200 price tag may be hard to justify for some. I got a great deal so they were worth it. I think a comparable sound for cheaper would be the M50s.
Hope this helps!