I received these headphones in addition to the standard Zune headphones (which are uncomfortable and not all that great) and was pleasantly surprised. The passive noise canceling worked surprisingly well and the earphones were very comfortable and stayed in my ears without much issue.
After a few months of use one side stopped working so I called up Zune support and they willingly shipped out a new pair of headphones. However, after a few months these also stopped working on one side. At this point I was a bit frustrated and opted to buy a different brand of earbuds. However, as long as they work these are excellent headphones with good bass and sound quality.