I'm more familiar with Bose's noise-reduction earphones, but was eager to try these because there are times (notably walking in New York, and trying to avoid being hit by a car) when you want to know what is happening around you. Also, while I've been quite happy with Apple's in-ear headphones for the iPod, I'm always on the lookout for something more comfortable that I can use for longer periods of time (a plane trip, say).
Well, these certainly fit the bill. They nestle lightly in the ear, and while they don't always FEEL secure, they remained in place during periods where I was doing my shopping, walking home and working out at the gym. Even moving my iPod around in my bag or my pocket and accidentally pulling on the headphones didn't remove them. And I didn't have to jam them tightly into my ear to accomplish that!
Another big plus is very low noise leakage. Yes, I know that's more for others' benefit than my own, but it's still an upside.
Best of all, of course, was that the sound was exponentially better than anything else I have tried. True, you don't remove the outer world as you can do with the noise-reduction headphones, but even without that, the sound is crisper and more clear, all the way through the spectrum. I've turned down the set point volume on my iPod; I now don't need to have it turned all the way up. Another plus for me: I transcribe a lot of interviews, and find that these are nearly as good as the noise-reduction earphones in doing so. (The regular kind don't measure up; too much outside noise creeps in and the sound isn't clear enough for me to catch each word.) That means I can do my work and still hear when the phone rings!
One caveat: I find it finicky to remove and then replace these. Even after a week of using them, I was still having to pause and remember which earbud goes in which ear, and at what angle. There's no "pause" button feature on the earbuds themselves, so if you need to have a conversation with someone in real life (in a store, on a plane, bumping into a friend on the street), you'll either need to yank out your MP3 player and turn the volume down or remove the headphones. After years of using in-ear headphones, I'm used to just putting them back in without really pondering which goes in which ear. There have been a few times when I've had to stop, put down my bags, and figure it out. I'll update this review in a few months to note whether this gets easier, whether the earphones are as durable as they should be for this price, how they function in freezing weather, and whether they are as comfortable as I anticipate on a long plane trip and survive without falling out. That would be a boon for those overnight flights, when an over-the-ear headphone is just too uncomfortable and the Apple-provided earphones tend to fall out.
For now, I'd say these are the best earphones of their kind that I have tried -- which they should be, given their premium price. Recommended to anyone able to put sound quality above price as a consideration. 4.5 stars, rounded down.