I've been using a pair of these for 12 hours a day for eight months. The sound hasn't changed at all, pretty crisp, decent bass if you adjust the equalizer on your player.
The only sign of wear is that there's a little give at the hinges where they fold for storage, they move side to side a bit. You can't tell while you're wearing them, they just don't fold tightly anymore. Considering how many times I fell asleep with them on it's a miracle they lasted so long.
I got a lot of compliments for them, they look really cool especially in an all-over colour. I'm getting another pair 'cause I got bored of the colour on mine, wouldn't replace them yet otherwise.