I have never had a Bluetooth headset before the 510.  I use it with a Motorola i870 Nextel phone.  The headset works great, sometimes it disconnects for a moment and I just press the button on the side of the headset and it reconnects.  The talk time is awesome and I have gotten almost 5 hours continuous talk time out of the device.  The range isn't too bad I think I can get about 30 feet from my i870.  If only my crappy Nextel phone could keep up will the quality of the headset.  Since my i870 battery goes dead in like 1 1/2 with the extended batter pack I have to plug it in to charge.  However, while it's plugged in I can still use the 510 and wander all over the house and still talk on the phone.  It almost replaces the phone if I could dial from it.  The best part is that when you get too far away it gets a little static so that you know to come back closer and then the sound quality clears up.  Everyone I have spoken with on the headset says it sounds very nice and clear.