Heavy, but Effective

Pros:
-They block out sound astoundingly well--I believe they were designed for air traffic controllers, which would explain it. They also do so "passively" (meaning the way they are built naturally blocks out sound--rather than "actively," which would require batteries).
-The sound is pretty good--mids and highs come through well. This is good if you don't listen to music with a lot of bass (like me).
-Although they are very heavy, they are well-padded around the top of the head and the ears, making them relatively comfortable.
-There is external volume control on the left headphone, which comes in handy when someone needs to talk to you.
-The chord is coiled, meaning it is naturally pretty short, but can extend if you need it to do so (which I don't).

Cons
-They really are heavy: about 2 pounds. I've gotten used to wearing them (maybe my neck muscles have strengthened), but at first this was a nuisance. I'm always afraid they're curving my spine :). Oh, and they flatten your hair.
-Very rarely (maybe twice in the 3 or 4 months I've had them) the headphones will refuse to play. I think this is due to a problem in the stereo/mono switch, because when I fiddle with the switch, it fixes itself.
-The stereo/mono switch (which is located about 8 inches down the chord), as I see it, is completely useless. I guess if you're running low on batteries, you could switch from stereo to mono and give yourself an extra five minutes of play-time. So far it's served only to accidentally switch to mono, causing me to habitually check back at the switch to make sure it's on stereo.
-You really can't take these babies outside. Not that you'd want to--you might get run over. But even if you did, they are gigantic, and you would get stares.
-The bass isn't great.