I've used many bluetooth headsets:
Motorola HS 810
Motorola HS 820
Motorola HS 850 (3 of them)
Motorola H700
Jabra BT 200
Jabra BT 250
Jabra BT 800
Jabra JX10
Plantronics 510
Plantronics 640
Plantronics 655
Flamingo (I forgot which one)
Tekkeon EZ talker
Call me a nut, but I just want to find a headset that is as clear as a wired headset. The Plantronics 510 so far is the most clear with my Treo 700w. But for the size and compatibility, the 655 is very good. Callers can't tell if I'm using a headset or not. The only thing I don't like is ...
1) When I have my phone on my waist in the case, there's a crackling noise
2) There is a "white noise" in the background that can get rather annoying if you're picky.
Besides that, the headset is loud. Tone isn't bad. Sometimes a little muddled because the the range of the sound may not be very great (small headset ... cant' expect too much) but it is a lot better than any of the headsets I've used.
The motorola hs 850 was great. the only thing was the sound wasn't as loud and the design was a flimsy even though I found the folding boom mic VERY practical.
A little about myself, I was a music major ... so sound quality is very important. that's why I'm so picky.
The 655 improves on the 640 in many ways ... little things that really help.
a) the 640 was hard to put into the charger and be sure it was charging. Move it around on your desk and it could easily "disconnect" from the charger. The 655 has not such issue and vibrates when it starts to charge.
b) DSP means a better signal, at least as far as I found
c) Very comfortable
Bad things: doesn't come with the nice case + power adapters that the 640 did. However, the adapters are the one accessory from the 640 that can be used with the 655.
I bought this 655 as a replacement for my 645 which got stepped on by someone. I loved the 645 but thought I'd try the "upgraded" model for the same price (thru Newegg).
While it was comfortable, I have used it for a week and no one can hear me talking. Everyone I have talked to this week has complained that all they hear is static or nothing at all. There has also been a lot of background noise and wind affecting it even when I'm just in a relatively quite place like Target. Also, while mostly I could hear well it would have static and cut out on me from time to time. It doesn't have the range that the 645 had.
My husband was so frustrated from trying to talk to me this past week we decided to return it and get my old 645 again, which I have loved and never had any problems with people telling me they couldn't hear me (I had it for 6 months). Also, like other users there is no good case for all the extra pieces, and of course you don't get as many chargers. For those looking to replace the 640 I would highly recommend the 645 over the 655. The 645 seems to have fixed many of the problems the 640 had, while the 655 just got new problems.
This is the best Bluetooth headset I've used with my LG VX8300 so far, but it still is far from perfect. I get roughly 2-3 hour of talk time out of this headset depending upon how long I leave it on between calls, but I assume that the battery life is a trade off for the small size and light wght. My biggest problem with the headset to date has been that it is extremely slow to connect to my phone when I hit the headset command button. With incoming calls, the call may roll to voicemail before the headset connects (if I don't pickup the handset and flip it open.) I've given up on using the voice commands altogether because the connect is so slow to get established.
As noted by other reviewers, the ear loop and gel ear buds work well until they pop off of the headset (usually while you have it in your pocket). I've found the ear loop to be vital to keeping this unit in my ear; the ear bud just doesn't hold it firmly enough to keep it from falling out in the middle of extended calls or while driving.
Despite the problems above, this headset (once it has connected to my LG VX8300) has had great sound quality and everything functions nicely.
I have a Voyager 510 which has great sound quality on both sides. Why do I continue to buy and test Bluetooth headsets??? Because I'm waiting for DSP to finally work and block background noise for the person I'm talking to.
This headset is equal to the Voyager 510 when in a quiet envirnment but if you're outside and a truck passes by or you're in your car and it's raining - sound quality for the other person is poor.
Sorry Plantronics - I love ya - but you're not done yet.....
I had been using this headset for a couple of days when I discovered that everyone on the receiving end of my calls with the headset said it was difficult to hear me because everyother word would be dropped out. I tried the headset on two different phones with different service providers and it was the same story so the phone(s) definentaly were not to blame. Basically, I could't move more than 2 or 3 feet away from the phone before the bluetooth connection began to get fuzzy and fall out dramatically....it is rated for 33' right?! Also, the earbuds are comfortable, but a PITA because they keep falling off, I had one of them break too! Overall, this headset is a nice unit that needs a fix in the range of operation. I can hear everybody perfectly clear, but they cannot say the same.