Pros: Good audio quality, good isolation, heavy duty cable and connector, very accurate, collapsible for storage
Cons: Uncomfortable over long sessions, leatherette cracks over time
Ah, the Audio Technica ATH-M50's. These guys have been reviewed to death and praised to high heaven. They were also my first foray into the audiophile category, and overall, I'd say I've been very satisfied with them.
The audio quality is amazing for the price, though it excels at nothing in particular; In fact, that seems to be their main goal as monitors. They provide an accurate, relatively 'flat' sound stage and frequency response, and in doing so aren't actually very 'fun' to listen to for extended periods of time. There isn't really much that can be said about them that hasn't already in this respect, and by no means am I knocking them for prioritizing accuracy over fun factor; Quite the opposite, I was delighted when I first received them and was able to identify for the first time many things I'd previously missed in much of the music I listen to. As monitors, they do a superb job, and I've used them for that purpose in the past.
There are some issues with build quality and comfort, however. The leatherette ear pads seem to crack over time, and these cracks are very sharp to the touch, which seriously impacts my ability to wear them for extended periods, especially combined with the well-known issue of excessive clamping force. That having been said, the cable is incredibly thick and the gold-plated connector is heavy enough that there's no doubt that it will survive a substantial amount of punishment, with a nice matching spring stress reliever in place of a standard plastic or rubber one.
Overall a great value, and a great entry into the audiophile market. They got me hooked for sure.