Were you one of those people who was expecting an upgraded M-80? If so, I'm in the same boat as you and is the reason why I'm disappointed with the M-100's.
I am satisfied for the most part for what it is though since I was originally looking into a durable portable headphone because my SRH940 was (now is) dying at the time and its sound wasn't very enjoyable for mobile listening. For that purpose only I really like the M-100's. For home listening I prefer the AKG K 701 or SRH940 even though its fit is "meh" due to the flimsy broken headband.
Yeah, I was blown away by the M-80. After the Creative Aurvana Live!, they were my introduction into GOOD headphones. I was hoping for an upgraded M-80 and I let the hype get to me. I'm going to give the M-100 some more time and yeah, I need an on-the-go can so I hope I can come around but I will definitely remain disappointed.