low build quality compare to any other Sennheiser headphones, including the sennheiser hd 201. silver paint on the black frame, paint bubbles, home DIY wires etc...
sound quality is good for the price i guess, but not a typical "Sennheiser" sound signature headphone, sacrificed mid high for more bass. hard to say its a good or bad thing but everything i love about "sennheiser" ar missing.
narrow soundstage, i don't know why some ppl said its "wide", maybe they compare it to a closed back headphone? but as an open-back headphone, the soundstage sux.
im not saying its a bad headphone, in fact that for $150 this is one of the best sounding (not build quality) headphone u can get on the market, but i was expecting something like paying $199(HD6xx) and got a $600(HD650) sounded headphone, the fact is more like a pair of $200 headphone cut some corners and sell u for $149.