They are great headphones (I use them for DJng) but not really ideal for studio work.
They are designed for monitoring sound in fair enough quality in loud enviroments, and at that they're very good. They are widely used by airline pilots, DJ's, sound technicians, etc... Good build as well, but easily start hurting your ears in longer sessions as they push against your head quite firmly.
For production the main problem is that they are what you call "closed end headphones". This is to keep outside sound from intervening, but it puts big limitations on the internal acoustics of the headphone.
For production you should get open ended headphones. They won't silence the outside world and they will leak some sound outside as well. But they will sound much better and are usually designed to be used in long sessions so they won't start hurting your ears after half an hour.
Sennheiser makes some really good studio headphones as well and my personal favourite brand is Grado.
Have a look at my blog post on the same topic (it seems someone already linked to it):
http://www.resoundsound.com/weekly-tip-23-headphone-magic/
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I might add though that if you're looking for good "all around" multi-use headphones then they are definitely not a bad choice. But if you need great headphones for studio work only, there are much better options around for the same price.