Pros:Fantastic design, great sound, attractive & accessories make it worth the extra cost.
Cons:A little pricey. Rubber earbuds may attract dirt.
The Bottom Line: Great headset for anyone looking to make use of a Bluetooth-enabled device.
Although it cost twice the other popular headsets, it's worth it. It includes a very sturdy, lightweight & compact carrying case for headset & accessories. The accessories include charging adapters for a few of the more popular phone chargers. I didn't get to take advantage of them but I'm sure many people can. It also comes with a AAA battery charger if your headset runs out of juice away from the wall charger. I think the extras are a very nice touch even if I personally won't need them.
Recommend this product?
The build quality is superb. Unlike almost every other headset I considered, the 640 doesn't need the earhook to stay on (although it comes with one if you prefer using it!). It is an in-ear design so if that makes you uncomfortable, be warned. Because it's so lightweight, you can just put in the earbud & it hugs your face very comfortably. The soft gel ear inserts are very nice too. It comes in three sizes, the default fit my ear & my wifes perfectly. It has yet to come out while I'm walking the dog, driving or chasing my kids. The sound is crystal clear & can be loud enough for anyone.
The first one I got was defective b/c the headset wouldn't stay in it's charging cradle securely. Plantronics shipped me a replacement & said return the defective one once you receive the new one. That is the best customer service I've ever gotten! My new headset is great, no problems charging.
The interface is simple & straight forward. There is one function button. It controls the power, answering/ending calls, redialing the last number (double-click), enabling voice command (if your phone supports it) & mating it with your bluetooth device. It also has a volume up/down toggle button that mutes as well. It took me very little time to get used to pressing that one function button for all the different uses.
The build quality is superb. I had dropped my original purchase several times because it wasn't sitting in the cradle correctly (it clips to your clothes like a pen cap if you like). The headset is so light that it wasn't damaged at all. Since Plantronics replaced it, I doubt it will fall again but if it does, I will not be concerned.
The wireless connection is very good. It has it's moments of crackly static if the phone is on the opposite side of my body or I walk too far from the phone but only on occasion. Like any microphone in the wind, it picks up wind noise so that's no shock. I haven't used other Bluetooth devices so I can't compare. But overall, I'm very happy considering there's no more wires to tangle or accidentally rip out of my ear while I'm turning the steering wheel.