I am a bit of an audiophile: I have owned over 20 or so models of earhpones and headphones, built by Sennheiser, Sony, Creative, Bose, Shure, Griffin, and even the Klipsch Image. I am happy to say that these Phillips Earhook's put up a good fight.
Comfort: these fit perfectly. The supplied rubber buds come in many sizes, and do not irritate the ear. The left wire length matches the right wire length, which is extremely important. The ear-hook is well designed and properly proportioned.
Noise isolation: EVEN IF THE EARPHONES ARE NOT PLUGGED IN, these will eliminate much of the background ambience. Perfect if you need to concentrate when reading something on a flight or in a public library without actually listening to music. That's how good these are.
Audio quality: Excellent mid and high tones. No noticeable static or hiss. Excellent for listening to classical music. Contrary to other reviewers, I found that the bass on this is very powerful compared to other earphones available over Amazon, except Klipsch Image (which are the best that money can buy, but they also are more expensive). Of course Phillips Earhook earphones will not give you as much bass kick as a pair of headphones, but at this price, the bass quality is a steal.
Build quality: these will withstand a good amount of wear-and-tear, and will hold their own in rain and wind. The ear-hook is sturdy. I wore these outside during the wind and storm a couple of weeks ago.
OVERALL: tremendous quality, even at this price. Judging on comfort, these are the best. Judging on sound quality, these come second after the Klipsch Images. Judging on value-for-money, these are a steal. If you are thinking about getting Shures, Sennheisers or Creatives, try these first, you will not be disappointed. The only drawback: no volume control wheel. But that is a very common drawback.