Well, the sound quality is excellent, no question about that. Extremely clear, nice base punch, crisp treble. Easy to wear. Great duration.
Minuses: Interferes strongly with wireless network (linksys wrt54gl and a wap54g). Moving the net-channels has no effect, so the only solution will be to move the sender farther away from the computer. And I'm a computer pro, so yes, I've tried to differ the channels as well. No change.
Like all others have said: the power-button is between the lower/higher-volume button. Simply not very well thought out. It is difficult to find, and if you are unlucky, when you want to pump up the volume you will accidentally turn the headset off instead. Then you will lose four-five seconds of the music until they resync with the sender.
Another minus: The Kleer-technology provides good quality sound, lossless, but unfortunately there is a decoding/encoding delay which makes the sound sound like an echo if you are listening to the source during loudspeakers at the same time. So all other speakers need to be off, including the speakers of your TV-set.
So in conclusion, I prefer my old Sennheiser HDR-120 to the brand new HDR-180. They have much much better sound-quality but losing the wireless signal, delay as well as other minuses are just too much of a disadvantage compared to the simpler technology of the HDR-120/140. I would return them if I could.