Ivisi hit the nail on the head...
First call I made to VZW tech support was a dud .. the tech new nothing and lost me in transition to get a "replacement" phone.
Called back, and got a lady who was very willing to help..we made a couple test calls and I noticed the "reverb" for lack of a better term..little bit of my echo..
Then she said, "Check your handset volume, these phones are VERY sensitive and the mic might actually be picking up the earpiece volume."
So I did, and it was full blast..and I turned it down a little and shazam it nearly disappeared.
She did say that Samsung is indicating (who knows if this is true, but I thought I read a post on some forum where Samsung had tweeted this) that they are going to be releasing a software tweek to address some issues.
So who knows..but for those of you who are noticing this issue, try this "fix" and see if it works for you.