I should also mention that the pro/con to the MW600 is that you need to supply your own earphones... so if you have ear phones that are comfortable and you really like, great, just plug them in. The other thing I like is that since I clip the MW600 to my shirt, you don't have to really worry about it being water/sweatproof since it's not dangling on the back of your neck or by your ears where sweat could drip down. And lastly, battery life is pretty good compared to the other options I looked at. I get about 8-10 hours of use before I have to charge again, which takes about 2 hours to fully charge.
I would say audio quality is about average. For purposes of working out/gym-use, that doesn't factor in too much for me.