Summary: Without the NR turned on, they are shockingly bad with absolutely no bass. With the (very limited) NR turned on, I have had to set the EQ on my Ipod to bass expander, and the bass is still very poor. The build of them is extremly flimsy. I had a pair of £15 Sony on-ear headphones previously to this and the sound quality was 10 times better! I would suggest you get them instead, or spend £100 on a decent pair of NR headphones - as I wished I had!! In a word - rubbish!
Summary: Firstly, let me say I bought these from the Sony shop in Vegas, not Amazon. The earphones work well as others say, cancelling out probably about 70% of the background noise. My main gripe is the flimsy way they are made. I took mine out today, undid them and they have snapped at the hinge part. Upon inspection I found the plastic is very thin around the part that provides the pivot so you can fold them. I suppose it's as someone previous said - you get what you pay for!
Summary: Lovely sound, good noise cancelling, but the band that goes over the head is a bit uncomfortable over long periods (not much padding on it) and, annoyingly, after almost exactly a year one of the earpieces has snapped off. So although they are technically still functional, I'm going to have to throw them out. Disappointing.