I got these headphones about a year ago. During this years I used these headphones on a constant basis. I had previously upgraded from the Sennheiser Amperior which hurt my ears (because the on ear design crushes the shape of my ears). Getting into the details
 
Build quality:
Where do I even start? The flimsy stainless steel headband. Some of the metal in the headband is cut out making it forked. Immediate when I first got it I was disappointed. It feels flimsy and it actually bends! I'm not kidding. I'm not talking about flexing. I think most headphone bands are flexible. I mean you can bend it into different positions. I shouldn't have to worry about bending my headphones. I have to mention this IN BOLD PRINT: The cables are crap. Both of the cables that came with the headphones broke within half a year apart of each other. There are two cables that come with the headphones. One with volume control and one without volume control. Both of the cables break near the plug that goes into your audio device. Cables that only last half a year are very bad. They don't work on android or old apple devices.
 
The look:
These headphones have leather on them. I didn't think about it when I first ordered them, because I was too enthralled with the good reviews to be thinking clearly. What the hell though, leather? Is this the stone age? Leather is very susceptible to wear. I had a leather jacket when I was younger and I couldn't wear it in the rain, I couldn't throw it in a wad, and it would tear and I had to get it fixed. It's not a practical material. The headband just curves around the head in kind of a unnatural looking way. It leaves a lot of space between the head and arches awkwardly. The earphone cups look average. You'd think I got these at a clearance sale at target for some headphones going for a faux designer look. I hate the way these things look. The Amperior (or the Aluminum as they call it now), kills this thing in terms of looks. I love the utilitarian look of the Amperior.
 
Comfort: 
I gotta give it to Sennheiser, these things are comfy. Much more comfortable than the Amperior. I can wear them on my head for quite a while and I never get hurt. So stars to the Momentum, for not causing me pain...
 
The Sound: 
So here's what everyone cares about. The sound. Well I'm not impressed. I tried a pair of Sennheiser Amperior headphones TWICE. The difference between the Amperior and the Momentum is the Amperior is fun, and the Momentum is dull. They're both detailed. The Momentum is laid back though. It has an edge over the Amperior in sound stage. It's not like the Sennheiser HD650 where I hear things coming out of the headphone and I have to take them off to see if the sound came from the headphones or inside the room. I listen to mostly extreme metal and hardcore punk type stuff, with the occasional indie rock, post rock, shoegaze, slowcore, folk, and whatever else thrown in for good measure. I'm kind of split between the sound of the Amperior and the Momentum though. Because while the Amperior was "fun", it wasn't actually that fun... it just had a brighter sound. The Momentums are not very bright, but they are a tad more spacious than the Amperior. I would choose the Momentums over the Amperior in terms of sound quality. Not sure if it gets much better in terms of portable. I'm just an average customer, not some tycoon who can test out all the brands. So I won't try to act like I have the last word on their sound over some of the experts in sound quality here at Head Fi. 
 
In conclusion, I feel ripped off. I know everyone likes these headphones, but they just have way too many drawbacks. I wish I would have gotten the V-Modas back when I was deciding what portable headphones to get. The new V-Moda XS just came out and I might end up getting those. I'm not sure yet. Don't buy these if you don't want to feel ripped off.

I have used and adored the Bose AE2 headphones for years. When I say I've used them for years, I mean I've really USED them. I have no doubt that I've used these headphones for thousands of hours. They work for everything. I fall asleep with them on every day, I go running with them and get them soaked in sweat. I've even wore them in pouring rain. These headphones have withstood the test of time. These headphones stack up to just about every other pair of portable headphones I have owned. They trample the Sennheiser Momentum and Sennheiser amperior headphones in terms of comfort. They're portable as opposed to the other headphones I've tried like the Hifiman HE-400, AKG K240, Grado sr80i, and Sony V6. They're also good for bike riding because they isolate from wind noise. These headphones also have excellent separation. When I'm listening to metal music, I feel immersed in the music, and there's not too much bass intruding on the other sound frequencies like the Sennheiser Momentums. I'm no audiophile, but I definitely think these headphones sound better than the headphones that cost more than twice as much. 
 
So you may be thinking, WHOA, this random dude is saying some mind boggling stuff. Well whatever, I'm not trying to change anyone's mind who already thinks bose is crap, and I honestly have no idea why people think that in the first place. I say if someone wants a pair of headphones to use for doing everything in, not to be used out of a desktop amplifier and dac, but instead out of their iPod like I like to use mine, hands down my vote goes to the Bose AE2. These headphones will love you, and you will love these headphones.

I've owned the Sennheiser Amperior for about a month and a half. I got these headphones for 175 dollars used, and I don't feel they're worth the money for me.Before I begin, I'd like to start off by saying some positive things so I don't come off as just bashing these things. I think they're very pretty headphones and they feel well made. They're fun to hold in your hands and appreciate the aluminium cups. They do have a rather quick and sharp sound. That's where I think the good ends. 
 
Wearing them becomes very uncomfortable after around 30 - 60 minutes of use. My ears get very hot/sore wearing these. I find that they are too aggressive for the metal music I listen to. I think there's too much bass and they don't have enough detail, especially for metal music which has walls of sound and there's not enough separation. For any music I think they sound too congested. I prefer a bit more soundstage. They may sound 'fun' at first, but I think these headphones, aside from the fact that they're uncomfortable, aren't easy to enjoy music with, they're just too bright and congested. 
 
- Minor Gripes:
 
-The swivel function for the ear piece is useless.
-The detachable cable is a bit bulky and thumps against my chest when I wear them for running. I supposed that these would be good for running because they're supposed to stay on your head very well, but my other headphones, the Bose AE2 actually stay on my head better when running, which I have used for running in for years (which are also vastly more comfortable headphones).
-You can't lay down with these headphones, even facing up on a pillow, because the ear cups fall off your ear breaking the seal. They don't actually stay on your head as well as you might think.
-When it's windy or when I'm riding my bike outside I can hear wind blowing against the ear cups, which actually makes it hard to hear the music. That is really annoying.
 
Thanks for reading.