I really liked using it with my shuffle, the sound was good, but....the connection on the back  strap hinge cracked off..I could still use it under my cap but... then  it broke at he hinge.
No way to repair it..  I treated it carefully and it didnt not last 2 swim seasons.

Need to try it a few times to get ear buds to stay in position for the duration of the workout. Using a swimming cap did the trick.
Love it!

This product worked well while treading water, but it was very noisy while swimming. I tried both methods of attaching it to my ear - the band it came with and the clips to attach to my goggles.

Pros:
It plays music while you are under water
Waterproof
Stays attached through vigorous activity
Cons:
Buttons hard to press
Ear sealers come loose, and have to readjust to hear music again
Hurts the back of my head due to boxy shape

My observations:

If you have a large head forget the headband.  It will not fit.  The goggle clips work fine but you need to test out where you need to have the clips.  I leave them on one pair of goggles at all times and simply rinse them off together.

The ear buds come in different sizes.  Try them.  I ordered some spares and those had a smaller diameter that fit my ears better.  
Do not buy extra blue tips which are what they show in the newer videos.   Those are used on the headphones that Natalie simply puts in her ears under her cap which are different from what I have.

The headphones  sound alot better underwater.   They are still not as good as regular Apple headphones out of water but they sound decent enough.  They are far better than nothing.

Bottom line this is a pretty good product that you have to learn how to use properly but is worth it if you like listening to music while you swim..

Good product.  No problems with seal yet.  If the band doesn't fit your head very well (as it didn't with mine) you have the option to remove it and attach it to goggles.  Wish the ear pieces fit a little better but if you secure it with swim cap it stays pretty well.