Summary: I have not used these on a plane yet, will take them to Europe in a few weeks to test on an airplane. I did however test them in my pickup back seat with my aftermarket exhaust system and actually had to look at the instrument cluster at the TACH to make sure the truck engine was still going. I could not believe how quiet these phones were and yet very clear music sound.
Pros: Light weight, great at cancelling noise and clear music.
Cons: The access to the battery compartment needs some work for easier replacement of the battery.
Summary: I was very pleasantly surprised. I had never before owned _good_ high-fidelity headphones, much less noise-canceling 'phones. I was skeptical, but I took a chance because I trusted Crutchfield's guarantee. They sound wonderful -- better than I expected -- and the noise cancellation is very effective, again better than I expected. I have fastened my tiny iPod shuffle to the headband just above the left earphone, and fastened the cable such that nothing dangles.
Pros: Excellent sound quality (with equalization); very effective (good enough for me) noise cancellation; light weight; and requires just one AAA cell, which lasts a long time.
Cons: 1. It's not waterproof, so I can't wear it in the rain. Also, I fear that my oily salty sweat will ruin its nice cushions. 2. It is not designed for anything to be attached. I wish my iPod could be attached to it more easily and neatly. Also, I'd like to be able to attach a security cable to it, so it weren't so likely to be stolen if left it unattended for a little while.
Summary: I can only speak to using these headphones for listening to music or movies during flights, but for that purpose they work very well, eliminating almost all of the "droning" and allowing a great listening experience without the need to crank up the volume unreasonably high just to hear your content over the noise of the plane. I much prefer these to the on-ear model but that is likely a matter of personal preference. Would recommend without hesitation.
Pros: Very comfortable, good sound, great for in-flight entertainment
Cons: Little pricey, somewhat large to carry around (though the included carry case is done very well)
Excerpt: These are wonderful headphones. Very comfortable and block out so much unwanted noise. I use them while riding the subway to and from work every day. I can actually hear my music over all the train noise! I would definitely recommend them to friends.