Headsets and me don't get along too well. They rarely fit my ear properly, they never seem to be loud enough (I'm not hard of hearing, either), and my biggest gripe: nobody can ever hear ME even when I talk at twice my normal volume.I purchased aMotorola H500for my mother as a Christmas gift, and tried it out myself a few times as I taught her how to use it, but found I just didn't like the way it felt on my ear...sort of like a barn door flapping in the breeze. People also complained about the sound quality when I used it...they couldn't hear me very well. And I found the buttons both hard to push and hard to find without actually taking the stupid thing off my ear, which completely defeats the purpose of a hands-free device. So when it came time to buy a bluetooth for myself, I did a little more research and the Plantronics Voyager 510 was far and away the top unit in terms of reviews here on amazon. Plus, there were a sufficient number of reviews (1066 at the time of this writing) to give me a high degree of confidence that "the verdict was in" on this device in terms of not just performance, but reliability as well.I'm pleased to report that it completely lives up to its promises so far. This puppy is LOUD if you want to turn it all the way up. And people can hear me properly for the first time in...well...ever! Even when I nearly whisper, they can hear me.PROS:- The earpiece fits properly and does not make my ear sore. The unit comes with several different foam earpieces so you can swap until you find one that fits you. I also like the fact that it actually inserts down into the ear canal, blocking out other noise and giving clear, loud sound.- It is a nice size...not too big, not too small. I realize they now have headsets the size of a LEGO brick, but there is such a thing as *too* small...easier to lose when it inevitably drops down between the seat and center console in your car...or (for gals) when it gets lost in the bowels of your purse. Plus, you would need fingers the size of a flea to operate something that tiny. I'll stick with something a bit bigger, thank you.- It looks cool- It folds up so I can hang it on a little desk organizer thingy I have...sort of like hanging a coat on a hook. Very handy and accessible when I need it- The charger cord "snaps" in place for positive retention that won't fatigue over time and give intermittent connection problems- The "turbo" button for starting and stopping calls is easier to reach and use than other bluetooth headsets I have used (i.e. Motorola M500)- The design puts all the weight behind the ear. Somebody thought this through in terms of how it ballances on the ear and where the weight is carried...like a backpack. Very comfortable.- Easy to swap for right or left ear use- Charges fast. Fully charged out of the box within 90 minutes (about half of the 3 hrs the manual said it would take).- Ear inserts are nicely engineered. The aren't just little foam "booties" that slip on over the speaker. They are rubberized and lock into place using an ingenious little spring-loaded twist mechanism. Very elegant engineering.CONS- The on/off button is a bit tough to use because it is so small. You have to press it with the edge of a fingernail. Just pushing with the pad of my finger doesn't apply enough pressure. Bear in mind that this is the on/off button. The volume up/down is easy to find/use, along with the turbo button (the one that starts/stops calls). Although the on/off button is also used to mute the device, I never use the headset for muting...I turn mute on/off from my phone because it has a flashing red light that tells me visually when I'm on mute...something I don't get when I mute using the headset rather than the phone.- No other gripes yet. I'll post updates here if I encounter any.At this point, my only concern is reliability. I have only had this device for one day, so I can't comment on how it will hold up over time. The device feels rugged, however, and the build quality mechanically seems to be very good. Nothing feels fragile or cheap.I really suggest that if you are shopping for a bluetooth headset, you seriously consider this one. So far, it is outperforming my wired headsets by a wide margin - all 4 of them!Also, you can find these new very reasonably priced. I bought mine on eBay for $35 (included shipping). It was in bulk packaging rather than a sexy retail box, but who cares? It came with manual, charger, and several replacement ear insert pieces. Here on amazon they seem to be going new for around $40. Considering how well this unit works, I consider anything under $50 to be a real bargain.(Incidentally, I'm using this headset with a Sanyo SCP-8400 cell phone. Paired up very quickly and easily. No problems whatsoever.)