the sound quality seems fine, have never really had anyone complain about it.
I need to adjust the volume at my end occasionally though.
I find the volume on my end tends to be high -- I'm always trying to turn it down. But sounds comes through clear and I've always been told I sound very clear, often clearer through this headset than directly through cellphone's speakers.
Always sounds ok on my end and people say I sound ok. Agree with abhisheksood about sometimes having to adjust the volume on my end here and there.
I guess I need to lend it to someone and try talking to someone using it myself. For now I've switched over to a Bose unit which is "ok".