Pros: Excelent sound quality, very comfortable.
I had this headphones for 3 months, and overall im very happy with this cans, the price paid for this hd439 was 99US, and i dont regret for buying them!!!
The sound quality is excelent, the lows are accurate and precise, not overbloated bass. The mids are very good, and the highs are somewhat recessed, but that's the way I like it. The sound signature of this cans are very relaxing, not in a bad way.
The comfort is unique in its class! With the cloth pads, ears do not hurt and the heat is less.
IMPORTANT: Out of the box, these cans probably dissapoint. But with some burn-in and a amp (i have a fiio e6 or fujiyama) you will be quite surprised with the change.
EDIT: If someone found the bass in this headphones light to your taste, you can mod this cans, is the same mod of the HD438. Search in this page and you will find it.