The AH-D7100's immediately became my go-to headphones for daily use since the day I purchased them three weeks ago.  They sound much  fuller compared to my Beyerdynamic T5P's and produce high sound levels with unamplified portable music devices.  They produce deep, rich, better-defined bass compared to my Ultrasone Pro 900's..   
 
Sound is uniformly clear and well defined across the audible spectrum.  Given their high efficiency, transient responses and punch are state of the art with  unamplified devices....the sound is powerful, an adjective usually reserved for amps. 
 
All these descriptions are good and well, however the most significant compliment I have for  these headphones is that they reveal details and nuances that go unnoticed with other cans, and that,  plus the quality of the overall sound,  make you want to re-listen to your music collection.
 
Aside from great sound, the Denons are comfortable  and listening fatigue has been minimal for extended periods.  Some reviews have panned the build quality and materials....I find the design to be modern, materials to be high quality and build to be meticulous. The provided accessories are also high quality (headphone stand, travel bag and alternate cables).
 
In sum:  Highly recommended.