i bought 3 pairs. one for brother, gf, and mother. We all love them. Works perfect @ the gym. Can leave ipod @ front desk charging while i go work out.

That ear piece design bothers me. I prefer the ear muff.

Let me offer my 0.02. Yes, you can exercise with them but if you sweat a lot, they are going to crap out on you. I thought my left earpiece died yesterday after mowing my lawn. After letting it dry out for several hours, it was back to normal.
Laying in the sun is a pain in the neck..literally. I have to prop my head up on a rolled up towel because the "box" part digs into my head/neck. wearing with sunglasses is a bit difficult too. Thats the bad.
The good is, the sound is great and the HD set comes with two differnt size ear buds (and two sets of the medium). They fit in my ears fine and do a pretty good job of keeping out extraneous sounds - but not sweat. The SRS WOW feature is good and has three setings to suit your needs. I use the third which seems to give a bit of boost to the bass. Overall sound, like I said is good.
Some people complain that the range is bad. I have to disagree. I get outstanding range around my house. I can leace my phone (HTC Touch Pro2) in my kitchen and walk around all three levels of my house and still get decent sound. Others have mentioned that you can't put your music player in your front pocket becuase you will lose your connection. I do not have that problem. I really think that has more to do with the BT transmitter/radio of some devices rather than the headset.
For me, it was a great purchase as I have snapped many wired headset cables by getting them caught on things. Not a problem any more. Overall, I'm very happy with mine. Maybe I should get one of those cool Nike headbands to keep the sweat out of my ears...then it would be perfect.
YJ