I've tried several different sets of earbuds in the past and my previous favourites, the sennheiser cx300, lacked the inline mic so I have been on the hunt for a good replacement for a long time.
I've tried a lot (skull candy, sony, JVC, sennheiser, radiopaq etc..) and either haven't been satisfied with the sound quality, or found that the inline controls didn't function fully with my iPhone 3GS.
These work perfectly, volume, skip track, call answer etc.. All work as you'd expect and the quality of the microphone is excellent for voice calls so they make for a perfect 'hands free' solution.
How do they fare with music? Superbly! I expected some compromise in sound quality as plantronics are well known for their mic/headset quality but not necessarily for their sound definition. I needn't have worried, bass is tight and well controlled, not the usual woolly or booming bass I've come to expect. Treble is crisp and the midrange is wide and bright. These really are excellent when it comes to reproducing complex recordings, jazz, classical, rock, folk, drum and bass, whatever the style these buds handle it with ease.
Don't look for anything else, these really are a great all in one solution that will serve you well for both your calls and music collection.