I got the Sony DR-BT101 headset today. After charging, pairing, and connecting it to my iPhone, I went for a walk with it playing my current audiobook. During the walk, I placed a call to a friend to see if everything is working properly. I've only been out with it this one time so far, but here are my impressions at this point.
This would not be an appropriate headset for those who don't like on- or over-the-ear headsets. If you want something small, light, and in your ear canal, or if you're going to be doing heavy exercise while wearing it, this headset is NOT for you. It is a bit on the heavy side, and it's definitely a bit clunky-looking. When I get the urge to exercise, I go and lie down until it passes, so these drawbacks are fine with me.
The spacing of the ear pads is a bit on the wide side, but I wear a 7-1/4 hat size, so that also works well enough for me. I only wear it while sitting at the computer or walking. I'm beyond head-banging while listening to rock & roll.
The sound quality is excellent for what I do. Mostly, I "read" audiobooks when in the iPod mode of the iPhone, and the sound quality was just fine. I did try a song, though, and it is true that the bass is a little on the lightweight side. If you're one of those guys in a low-rider Honda who drives around entertaining the whole neighborhhos with your subwoofer, don't buy this headset. I prefer a "brighter" sound - not so much high in treble as midrange, and for that this set is excellent, but the bass could be increased a bit, even for me. This is no biggie for books, which are crystal clear and easy to understand through this set.
I didn't experience much in the way of dropouts as I walked for approximately two miles around the neighborhood. I did have a few, but not many, and they mostly occurred if I reached up to re-position the headset or took the phone out of its holster. Could be my arms or hands were interfering with the antennas a little bit. One negative thing I did notice was a fair amount of clicking and popping on my end during the phone conversation...not enough to be REALLY annoying, but enough to wish it wasn't there. My friend heard none of this on his end and said that there was hardly any of the usual Bluetooth "echo" sound. He said I sounded almost like I was using the iPhone's built-in microphone, and better than I did with the Monster in-line wired microphone.
I have no idea what is causing the clicks and pops, but that was the biggest downside of today's experience with this new headset. Since I'm more concerned with listening to books and my only interest in phone calls is the ability to take them and interrupt the book without having to handle the phone itself, this is not a deal-killer for me. It might be for some of you, though. I am curious why I have them, but I can live with them.