Pros: Bass is articulate and solid, tons of punch, very detailed highs and mids (even if the mids are a bit recessed), great build quality, beautiful
Cons: Too bassy for audiophiles, ear pads could be softer (hurts ears after too much use), limited soundstage
This is a really fun headphone, especially for on the go use from day to day. The bass is really nice and punchy, but it isn't that annoying "Beats Solo HD" rumbling bass that gets in the way and muddies the sound. It almost has a slightly held back, but warm round-ness to it. It makes rocky music and a lot of tight indie music (see Grizzly Bear, Arcade Fire, Morning Benders) and some hip hop sound great (see Earl Sweatshirt, Nujabes, DJ Cam, Blackstar), but they don't have the thumping sub bass of something like a Beats, Sol, or even ATH-M50 can that allow you to hear the raw bass energy of music like Trap or Dubstep, both genres literally designed around that sound. You probably won't want to listen to classical music or jazz on these either to be honest. The level of bass that IS present is still to much for very highly detailed music that would be better listened to on a home audiophile setup.
These are headphones that can also go straight into a cell phone and be properly powered as well, making them a very odd device. They're for portable use, and sport a solid bass emphasis, but don't feel right for dubstep, trap, or even more bass heavy and/or aggressive house music. Who are these headphones for? I'll tell you who, me. They have a perfect sound signature for listening to indie music, or more experimental electronica (Aphex Twin, Burial, etc.) on the go or at a school, which happens to be EXACTLY what I bought them for. I'm a huge indie music head, and being able to listen to the chill but uplifting jams of The Shins, or the crashy rocking energy of Tame Impala on the go is just a treat, and the fact that you get that premium look and feel that Sennheiser have done so well is an incredible bonus. I guarantee that people will compliment you on them everywhere you go.
In short, they're a classy, but not quite audiophile Hi-Fi level headphone that is perfectly suited to rock, indie, and some hip hop and electronic music on the go.