When it comes to noise isolating earphones, Etymotic Research is up there with the best. If you're looking to buy a set of earphones that will significantly improve the audio experience from your player, then Etymotic should definitely be on your short list, along with Shure, Ultimate Ears and going by recent form, Klipsch too. But this particular set of Etymotic earphones, has a neat trick up its sleeve. You see the hf2s aren't just earphones, they're actually a complete hands free solution for anyone that uses their iPhone as their music player.
The problem with having a separate MP3 player and phone, is that when you're listening to your music, you miss all your phone calls. This was a problem that I encountered regularly when I was wandering around London attending Press events - obviously I didn't want to walk the streets without music, but the result was a plethora of missed calls when I arrived. That all changed when I picked up an iPhone last summer, and started to use it as both my MP3 player and phone. From that point on I could listen to my music, while safe in the knowledge that if my phone rang, I'd know about it.
The transition to using my iPhone as my music player was made complete when Shure released its Mobile Phone Adapter, which allowed me to use my E500 earphones with my iPhone, while also giving me full hands free functionality. Now, great as this solution is for anyone who has Shure earphones already, it's not the most elegant solution, and if you are looking for a decent set of earphones and hands free functionality, an all in one solution could be a better bet.
There are, of course, several earphone/hands free solutions available for the iPhone, including the woefully poor set that comes in the box. However, if you wanted to seriously improve your audio experience, your options were limited, to say the least. And this is where Etymotic comes in with the hf2s - Etymotic's reputation speaks for itself in the sound quality department, while the design team has also clearly worked overtime to create a product that's as unobtrusive as possible, without compromising the audio.
The hf2s remind me of the Etymotic ER.4 microPro earphones that I reviewed a couple of years ago. The single armature drivers employed by the hf2s allow for a very slim and lightweight design, much like the ER.4s and, in fact, the recently reviewed Klipsch Images. However, the hf2s aren't quite as comfortable as the Images, and you can definitely feel that you have them in your ears - but then the Images are just ridiculously light and comfortable.