tl;dr,
Very good headset for the money. Very balanced sound at all levels.
Full review,
It is lightweight, but not as comfortable as I expected and feels a bit heavy. Someone with a smaller head might find them more comfortable. However, they are not terribly uncomfortable, you just feel a little stiffness in the ear cushions after 2-3 hours. Personally, I wear them for 8-10 hours a day at work.
The build quality is average, everything is plastic but it seems like it will hold up. This is something we will see in the future.
The cable is quite long, I would have liked it to be detachable. You can't easily fold them in any way to transport them.
The appearance is very nice, but that is subjective.
The isolation of external sounds is quite good, especially for this price range. More expensive solutions are much better, but the HD 200 Pro does its job adequately in this area.
I haven't received any complaints from my colleagues when I turn up the volume. However, I think they sound a bit loud to others at high volume. In an office environment, where there is already a certain level of noise, it is imperceptible. Maybe for home use at night, while the other person is sleeping and you want to listen to dubstep at full volume, they may not be ideal.
The sound quality is excellent, to the point where you seriously consider whether it is worth getting more expensive headphones. Personally, up to €150, I don't think you can find other headphones with better sound. Beyond that, you go for Audio Technica M50x.
The sound balance is very good and the bass is neutral (as it should be) and doesn't have much distortion when you increase the volume.
Personally, I listen to music flat, but you can use an equalizer to adjust the sound as you like, and it gives you a lot of room to play around before the sound starts to distort.
In conclusion, I recommend them.