I fly over 200K miles per year and would never fly without my QC3's

I am on an airplane every week, sometimes twice a week and have used Bose noise cancelling headsets for the past five plus years. I've had several models but the QC3 is the best.

Design: they fold up and come in a case that fits easily into my Tumi bag and the case is fairly rigid which protects the headset. These are the newest ones from Bose and fit "on the ear" as opposed to the older QC2's (I had two of those) which fit "over the ear." The case, while smaller than the QC2 is still big enough to also fit an iPod--which is a great idea.

Battery: I initially was hesitant about getting this upgraded model since I literally only use them on an airplane and 100% of the time when the battery on my QC2's went out I used changed the battery on the plane and thought that if the battery went out on the plane with the new model I'd be out of luck. Don't worry about this though as the headset will blink red when you have FOUR hours left alerting you that you need to charge the battery. It comes with a small battery pack which will recharge the battery to full capacity in about three hours. The good thing here too is that you don't have to let the battery run down before recharging as Bose has done something with the battery where it does NOT create a "memory".

Functionality: These headsets simply eliminate nearly all engine (and kid) noise from the jet engines. I could not fly without them and interestingly enough American Airlines has recently put them in their "Flagship Suite" service (First Class) on all of it's 777 aircraft.

Other uses: I really don't have experience other than on an airplane but a flight attendant told me she sleeps with them on to take out the noise in hotels (I don't see how that would be comfortable but it works for her). These headphones would probably be small and light enough to listen casually but are much larger then ear buds.