I am experiencing the same problem you refer to.
I have the MBL for about a week and am trying to back up my videos on MBL ( 760 GB size) and the system is telling me an estimated copy time of 162 hours.
I am using MAC (Snow Leopard).
I have checked deactivating the wifi to make sure it was not using it instead of the direct cable, but the speed has not changed. I have left the copy going on for 30 hours and it has only copied 131 GB so I guess the estimation is real.
The same problem sims to be afecting the Time Machine back up, that is also taking for ever to make the first 1TB backup.
Previous to this situation, I suffered from a problem of the system not recognizing the unit but this got solved spontaneously soon after I askef for help to WD.
Thanks for your help.