I've been rockin' these babies for around 3 years now. Not only are they still in perfect working condition, but they're also super transparent (not too heavy on either end of the spectrum). I often use them while mixing and mastering, and even recording, even though they're semi-open.
One thing I'll say after having had them on my head a number of hours now is that they're not the most comfortable headphones around. If you've a massive head as I do, these might end up hurting after a bit. I often find myself having a headache only to have it go away as soon as I take the headphones off. Still a great purchase as far as bang-for-your-buck. If you're hurting for money and need to step up your monitoring situation (if you don't have near field monitors that is) these will serve you well.
They're also great for listening to music, which I often do and recommend doing, if you're planning on mixing with them. Once again you'll find they are really balanced. Also, it's obviously a great way to getting to know them in case you decide to mix with them.
Too long, didn't read: overall they're a great product but beware of the slight physical discomfort that may ensue.