Pros: Sound quality, Looks, Price/Value, Design
Cons: Clamp, Pleather Earpads
The M50 is without question, an excellent studio headphone that really strikes a great price/performance ratio.
The bass extends quite well and is never overbearing.
Mids are present and very articulate.
The trebles are the biggest surprise in that they, IMO, are balanced wonderfully relative to the other frequencies. I haven't found myself wanting more clarity or sparkle yet!
The fact that the M50s are just as useful with my iPod as they are in a studio makes them very versatile and a great buy. If you can pick up used for around $100, I'd recommend pulling the trigger.
The only negative about which I'll comment is that the pads, like many say, can make things uncomfortable after long sessions. The pleather is just low quality and can make ears hot or sweaty depending on how long the session is.
If you're interested in upgrading your Beats or Skullcandies, look no further. The ATH M50 will retain the fun sound sig while boosting clarity and overall depth for a very budget-friendly price.