I realize this review is about the BT500, but a little history is in order. I travel a lot...about 200,000 air miles a year. So I need a headset that I can use all day with my 5300 series Blackberry. This one comes pretty close, but could be better. My previous two headsets were Plantronics units (M2500 and Discovery 640). Both of these units had quirks and very limited talk time. I read a lot of reviews about the BT250 and figured the BT500 would have improvements over that one.In general, the BT500 works pretty well and it has excellent talk time (at least 6 hours), but there are three quirks.First, the bluetooth transmitter is very weak. If your phone is on your left and the earpiece is on your right, or vice-versa, the connection is terrible. I've had to stop using the thing at least a dozen times in airports because of what I think is interference from other phones.Second, the design of the little buds that go in your ear is wrong. No matter what size tip I use or how I adjust the device, I can't get the tip far enough into my ear to actually hear much. (At first I thought it was volume, but now I end up having to walk around with my finger on the unit pushing it into my ear a little farther. That kind of defeats the hands-free purpose, don't you think? Maybe it is just me, but I don't think so. I have plenty of earbuds that fit just fine.And the last quirk is the power/USB jack. Guess what? In spite of the description, it is NOT USB. You need to lug along a little adapter cable (USB type A on one end, proprietary on the other) that connects directly from a PC to the phone. This guarantees that you can't use your Blackberry or Razr car or A/C charger, you have to buy stuff from Jabra, and you have to lug around yet another cable. (Why everyone can't just standardize on mini USB, I don't understand.)So although the BT500 seems to be a big improvement over previous models, it still isn't quite right.