Just alright
Not great, not horrible. They fit well, but the sound quality kinda stinks. I wouldn't recommend them. I used to have a similar pair that were made by sony/nike... loved those. Thought these would be the same, but they're far from it.

Couldn't be happier
I bought these headphones almost a year ago, and I LOVE them and have never had ANY problems. At first, you have to get used to putting them in, but once you get the hang of it, it's second nature. I bought these because earbuds ALWAYS fall out of my ears while I'm running, and when I got the headphones with the speakers outside my ear with the plastic attachment to go behind the ear, they were too bulky and the plastic attachment wasn't flexible. So, these earphones are a mixture of just what I wanted and are perfect. They stay in because you bend the "flexible earhook" all the way behind your ear, and I have never had a problem with them falling out or shifting.

The only problem I could see someone having is that the cord is a little short. I wear my mp3 player up high on my arm, so it's perfect because it reaches with room to spare. They do come with an extension cord, so, if you don't lose that, you should be fine. For an example, in the airplane, the headphones won't reach plugged in to the armrest when i'm leaning back in my seat. SO, if you wear your mp3 player on your shorts or carry it, you may need to use the extension. I haven't recognized any loss in sound quality using the extension.

Only one other hint - when you get them, the comfy felt coverings that go in your ear are not on the speakers (they are not in the picture posted on amazon). Therefore, you have to put them on yourself, and I ripped one of mine a little bit because I wasn't careful. So, if you're going to put them on, be gentle.

Nice idea - poor implementation
I bought these headphones to try something different from standard apple headphones. but - how disappointing - and bordering to misleading.
The "extendible" feature is a very heavy metal connector which makes these phones unusable for anything like running or biking. Also the behind the ear foldable things keep on getting tangled up. Back to basic apple headphones for me.

Did Nike do any product testing?
I'm shocked at how horrible these earphones are, give then price and given they are from Nike. For daily use and around the gym they're comfortable to wear and almost unnoticeable, but the earbuds sit so far out the ear that you have to turn the volume up a lot to drown out the music they're playing in the gym. For running they are completely useless. The constant bouncing of running caused them to fall out in minutes and unless you carefully manage the cord, the slight weight of the cord bouncing caused them to fall out immedatiately.

Someone at Nike needs to be fired.

I'm going to return these...
I liked the fancy white to go with my green nano. The sound is great and the fit is too. I have small ears and these stay put BUT the damb cord! It's short for arm band users with an extension for waist lenth. The extension part makes it heavier and now it bounces down until it starts to pull at my ears. ANNOYING! I have to readjust the cord each half mile or so.