No complaints about the earpiece, I've bought several for my company. But if you break the earloop (and you will ventually), you'll have an unusable unit because the Jawbone folks have decided to discontinue the replacement item. Be warned: the earloop for the new Jawbone II WILL NOT WORK with this original unit.

I've owned Motorola, Plantronics and several other bluetooth headsets and got really tired of having three fourths of people tell me to call them back when I'm not using the bluetooth headset because they couldn't hear almost anything.
The Jawbone's worked perfectly from the start.
I've had a couple of hassles with the ear-piece, but this is finally a bluetooth headset that I can use. I'm happy as a lark

First let me state the things that would be 5 star worthy. The technology in the noise shield is nothing short of mind blowing. On a city street with buses and loud traffic or sitting in my hotel room with no noise, people I talk to can't seem to tell the difference. I also having tried many Bluetooth headsets can say I can also regardless of noise hear better on this unit than others.
Now, the less than a star what were they thinking part. It doesn't fit well and I don't care how much you fiddle with it. The way the earbud attaches sucks. Half the time while trying to get the fit right I turn it the wrong way and it falls off in my ear. The buttons make a crunch noise when you push them like the unit is breaking. When unplugging the unit from the charger it always feels like it will break even when you do it exactly like the customer service jerk tells you to (mine actually did break recently unplugging it).
And still... the technology works so well it is worth overlooking these problems and buying.

Bought 2, sound and quality of device excellent, The wire for the device that hold on ears is very poor and breaks very easily. Had to order replacement parts the first week. Would be outstanding device if the wire hold would be corrected.

One of the best at noise cancelling. Only complaint is the ear piece doesn't fit as well as some of the others and therefore you don't hear as crisply as you might like.

Otherwise though, its pretty darn good.