Sound quality is outstanding, even though some might find the treble a bit painful on some tracks. But that can be corrected by personalizing the frequency response through the MIY app.
Among the most comfortable headphones you can find, you can wear them for several hours without feeling any discomfort. However,the fit is somewhat loose. The headphones have to be really well positioned for staying in place and having a good seal (which is necessary to enjoy correct bass). If they had a slightly greater clamping force and/or better sealing earpads, they would be perfect.
A bit too bulky for making them a good mobile option though. It's nice to have a hard case but it takes a lot of space in a backpack. Besides, you have to keep the headphones on your ears. The cups are so big that you just cannot wear the headphones around your neck.