These headphones have good sound quality considering the fact that they are wireless. They don't really "bump" so to speak and the bass is nothing too fancy. If these were noise cancelling then they would be next to perfect as far as wireless headphones go. The design for these head phones allows for comfortable walking and basic seating arrangements but don't attempt to get too comfortable because the connecting plastic arch that goes around the back of your neck will bother you and/or push the headphones off of your ears or push them in a way so that they are not completely on your ears(that alone will drive you mad). as for running with them I wouldn't advise it as I've tried it before and they have a tendency to fall off of one or both ears and when your head gets hot the abrasive foam pads that cover the actual speaker rub your ear and make noise. The friction makes your ear hotter and if that doesn't bother you, the sound from it will. These headsets were designed for people with medium to small sized heads that have thin or no hair. I have a head full of thick hair and when I spread these headphones apart to put them on my head, the round plastic arch in the back snapped almost completely in half. Attempts were made to glue them back together and for a while it worked out but I got over-zealous and they snapped again. Be careful of this should you decide to buy them(accidental damage is not covered by the warranty...I checked...well at least in the U.S). There are two pieces to this device as I'm sure you know, second we have the transmitter. This piece of the device is not too small as you would expect of anything bluetooth related. It is rather large and it can make an iPod seem significantly larger by about 2 inches and it will barely fit with any ipod case you may or may not have on(iPod skins work okay). As for other audio devices, it's rectangular shape warps anything that isn't shaped like it. It's good to have sitting out or behind something like part of a sound system but to attempt to put it in your pocket will prove quite irritating. Connecting the two is all too easy. You can even connect the headset to your cell phone if is has the ability to send music files out to bluetooth music headsets like the Nokia 5300 or others(check your phone for possibilities). One last thing. If you didn't know this already, bluetooth signals can be scrambled by microwave frequencies quite easily so if you're jamming to some tunes and heating up something in the microwave you won't like what you hear if you're too close. The battery life is very impressive. I've fallen asleep for over 8hrs with them on full volume and when I woke up they were still kicking. Over-all it's a good product with some design flaws that cannot be overlooked unfortunately, but once you've made peace with them the product isn't all that bad.