These little earbuds sit nicely inside your ears and block most of the outside world so you can enjoy your music. You will still be able to hear passing cars and such, but general ruccus is cut out.
In use, there is very little sound leakage because of the smaller in-ear speaker at the end of the bud, and changing the tips on the end of the bud allows for exelent noise isolation even at high volume.
The microphone on the cable itself is very sensitive, so you won't find yourself shouting into it, however the operation buttons can be a little fiddly, and may only work with certain smartphones. (Iphone, some blackberrys/most HTC phones)
overall they are very stylish, have good sound quality and are amazingly cheap for how good they are. Even if you don't intend to use the built in microphone feature, I reccomend you get a pair of these for their performance.