Pros Excellent isolation
Cons Lack of sound definition and light on bass
Summary The best thing about these phones is the isolation (I believe they say 32 db). This is both coming and going - it keeps the headphone sound in and the outside sound out. This is great, for example, in our small studio when recording exposed vocals.
But the sound reproduction itself is only good. Bass is suprisingly weak; mids and highs lack clarity. Sony's MDR-7506 is our reference point for $100 headphones. The Sony's don't have any bass either (and don't give nearly the isolation). But the 7506's are noticibly crisper on mids and highs - a much more plesant listen if you don't need the isolation.
Pros Comfortable ear cups, great isolation, proper cord length for office, excellent all-around sound for all types of music
Cons No headband tension adjustment
Summary I work in an R&D office adjacent to an automotive/fabrication shop. These HD 280 Pros isolate the air impact sounds wonderfully. Largely listening to trance/techno/house, I found these to be accurate, clear, and responsive to all frequencies. The sound is linear at all but the highest levels. I sampled the Eagles and Norah Jones to get a feel for the fidelity and was impressed at the audible nuances that I was missing. The design is basic but well-built. The headband is comfortable, albeit an adjustable tensioner would be nice. Faux leather ear cups are supple and my big ears don't hit the inner linings whatsoever. Coiled cord length is great for PC or MP3 player use. The screw-on adapter is a nice finishing touch on an excellent pair of closed ear headphones.
Pros Rich sound, very comfortable, lightweight
Cons Lots of plastic! Break-in period.
Summary Please please listen to people when they say give them 24 hours or so of high volume break in before you judge them. I just plugged them into my Zen Touch and let it play at full blast for about 24 hours. I put them on every so often to listen and I could hear a huge difference in the sound as the 24 hours progressed. Give them time, you'll be amazed at the diference! I have a big head and they fit very well, since there seems to be some question about this. Sound is unreal! I have listened to them on my laptop with movies as well as my Zen Touch and iRiver 790 (both highly recomended MP3 players buy the way). Just like everyone else says, you here things in your music and movies that you were never aware were even there. Well worth every penny. X10.com has them for $84 right now with free shipping. Best deal I could find. They are of course a little big, but hey what do you expect? They are full size headphones...duh! They are not going to be as portable as earbuds or smaller headphones. They do fold up quite nice, but are still not going to fit in your pocket. They seem to be made out of a lot of plastic, which may be a downside, that remains to be seen over time. I prefer things to be solid, but obviously that adds weight. I highly recomend these headphones
Pros Very detailed sound
Cons A bit low on bass
Summary These are some great headphones! The sound is just amazing. At first it seems like the bass is too low, but after a while you learn to hear the way these cans reproduce the bass and then they just rock! I love the extremely tight bass they have. But they ain't the most pretty headphones I've seen. In fact they are pretty ugly and you look kind a stupid with them on, but on the other hand they sit very nice. You can wear them for hours! Buy these headphones for the sound, not for the looks.
Pros extremely clear highs, good bass response, near silent at full volume
Cons Even the claimed 6N pressure on your head can feel a bit tight at times
Summary Ok, if you're a music lover, but don't feel like spending a fortune, these are the headphones for you. The highs and mids are extremely clear and crisp. I find the bass response to be just right, though some may find it to be lacking slightly. Again, it is needs-dependent. For a good comparison of the lows to highs, I recommend listening to Jesse Cook's album "Gravity" all the way through.
The noise-cancelling ability is second to none, for the price. I can turn the headphones almost all the way up (which is extremely loud, by the way) without anyone else either hearing or complaining about my music being audible to them. I was considering the Sennheiser HD-555's as well, but I decided I needed the better bass response instead of the open-air design. I tested both, listening to different types of audio (music, movie, radio), and found the HD 280 Pros to be much more suited to my needs.
If you have any circuit-building skills, I highly recommend building a pocket amp for these babies. The sound coming out of your portable sound source (iPod, cd-player, etc) will be much clearer and also have better bass response (dedicated capacitors for sudden, unexpected sounds like big bass drum hits).
To conclude, I highly recommend the HD 280 Pros to anyone who is picky about sound quality, but doesn't want to blow a huge wad of cash on getting it. They are worth every penny of the money I paid for them.