I use these at work and find that they are considerably better than the single ear piece version, the reason for this is i work in aloud call centre environment.
I have only recently switched from my single ear piece setup and can say the sound quality is a lot better, maybe that is due to the surrounding noise is not a distraction as much now. They fit my head comfortably and are adjustable to suite most size heads. The foam on the ears is nice and soft and doesn't become to uncomfortable whilst wearing them for a long period of time.
The headset is also nice and light which is a bonus.
Hygeine is catered for with the Plantronics headset as the mouth piece microphone is removable and you can buy replacements cheaply.
It is vital with these headsets that you use the mouthpiece extension as the sound quality is loads better and plenty loud enough, without it it can be hard to hear what you are saying.
Oh and make sure you adjust the mouthpiece to be right in front of your mouth.