I bought them one month ago... and at the beginning I was not impressed about their sound - they don't seemed very clear and the bass was just not right...
BUT (even I don't believe too much in burn-in), after one month of use almost every day, they are now much much clearer and the bass was also improved (but still not very good in comparison with IE80 for example).
 
I don't know if it was the burn in time or it was just a psychological effect, but now I just love them. The sound was SERIOUSLY improved.
The sound is now awesome, I can hear all the details, is very warm and easy to listen, they are very comfortable and, as I use them mostly in the office, I have observed that they have a minimal sound leakage - even with very high volumes.
 
Another positive aspect it is that they do not distort even with the volume turned above the maximum level... the sound is still very clear. 
 
The only CON that I have for these headphones is the bass - not punchy and completely without personality (sorry but I can't find a better word for this). But this is in comparison with IE80 which I also own... and love.