Sounds like the usual HTC crap earpieces to me. I can use full volume when talking to some people, others make it distort a little and I have to turn it down. But, it sounds no better or worse than any of my other HTC droids.
The Speaker sounds a lot better than my Desire Z though...probably not as good as the SGS speaker but I can hear more of the music and it is a little clearer...though the DZ is known to have a terrible speaker!