I had some fears when buying Bose's headphone, and actually the shop test did disappoint a little. But I like Bose products and virtually forced myself into buying this.
I tried it at home with DVDs and it had a suprisingly good bass and treble and I got a better feeling. Then I brought it to the actual test on an airplane. That is I actually have bought it for. And it performed admirably. The disturbing low freq noise from the engine was eliminated, and with the supplied adapter event the airplase lousy sound system was boosted a lot. When connecting it to my iPod, it was event better. I was just listening to the music, which is clear and dynamic. These travels last about 5-6 hours, and the headphones are on my head the whole time, and I do not get tired wearing them. Even sleeping is possible without any discomfort, although when the headphone touches the seat, the noise-cancelling decreases due to the mechanical vibrations. But still I could sleep in quiet comfort. (I have to admit here that sleeping habits are big factors in the comfort you will get.)
The battery life is quite considerable, if you keep one spare in the supplied holder, that should cover you in all cases.
Other places I have found it useful: trains (the track-noises are quite nicely filtered out), and rooms with old ACs (e.g. you are watching a DVD on your laptop). I have never tried sleeping it them in a noisy room, I guess that would be a real challange for the headphones. But it might come to that one day.
As could-be-better: the cable holder in the box is quite small, if you want to keep all its stuff with you at all times (e.g. you are a "never know what could happen" person, like myself) it can be a pain to pack the things together.
But in conclusion: I am a happy customer, and want to recommend this headphone for all people who travel a lot on trains or planes. There was never a moment where I have regretted forcing mysefl buying it.