This is my second pair of the BT620 headphones (my wife stole the first one). I am almost an audiophile and these headphones are good enough for me. The bass levels are pretty good and all the rest of the frequency distribution is balanced. For talking on the phone I have tried it with 2 blackberries (7290 & 8820) and a Nokia. This works well with all of them. On the 7290 the audio quality is better than the built in microphone and speaker. These cancel out an appreciable amount of background noise as well and makes talking from a crowded place without shouting quite natural.The headphones fit quite comfortably. I can wear them through the 10 hour work day (of course off during lunch) comfortably. Same with my wife, and our head sizes are not the same to say the least. The headphones feel flimsy the first time you take them out of the box, but are quite sturdy and can take a lot of abuse. (I have had one pair for about an year and still is going strong.)I am an electrical engineer and work on bluetooth enabled products, so you can imagine there are at least 10 different bluetooth connections in my environment continuously. The headphones never have any trouble even in that environment. The range I get is about 20ft through walls and a lot of metal.As I said I wear them through the 10 hour work day and have never had the battery die on me. I leave it charging for the night and the next day they are back to normal. I guess the older headphone should be coming to the end of its battery life because of being deep cycled continuously (Li Ion batteries don't take that well) but I think finding an after market battery replacement should be pretty easy for them. They use a standard size single cell 320mAh battery.I would definitely recommend these over Logitech Free Pulse or their older model. I tried those out before I got my second pair of the Jabra, and was not satisfied with them at all (Uncomfortable and bad bluetooth connection).