i have these, and they're great (sound good and have reasonable isolation; they're also pretty much indestructible, and reasonably efficient, so perfect for travelling) BUT they're not active noise cancelling. if you care more about peace than music quality you probably want something active (and if you care more about music than peace you may want something open - these are a compromise, which is a good thing when that's what you want, but be aware of that).

tl;dr - if you're willing to give up some isolation (compared to active) for better music, these sound good, last forever, and won't bother coworkers.