I'm wearing a pair right now. I bought them because my m50s are 3000 miles away. I plan on giving these 45s to my girlfriend when I get my m50s back. It's hard to compare the quality, as these haven't broken in yet (They're only a few days old now), and I haven't listened to my m50s in months.
Impressions so far:
Physical: Not quite as comfortable on the ear, as the driver is pressing on them. If my memory serves me, the ear pads seem nicer, and the headband is more padded. More comfortable than everything else I tried in the $100 range, by far.
Audio: I can't hear the dogs whining if I've got music playing, they cancel outside sound really well. The sound doesn't seem as full and deep as I remember but I really can't put much faith on that. I'll try to come back and respond when I get my babies back.
Do I regret buying them for a crazy good deal? Not even slightly. As usual, you get great quality for the dollar with ATH. They're not as wonderful as the m50s, but they're certainly better than anything else you'll find under $100.
Peace, Love, Music