I started using my ipod with this waterproofing device about 2 months ago and I love it!  I swim harder and longer because my music motivates me.  The time also seems to pass quicker and makes for a less boring work out.  Figuring out which ear buds stay in properly was a little tricky and took a couple different days to get dialed in properly.  They also need adjusting on occasion, but I do that when I take brief rests on the wall.  Overall, an excellent product, and I highly recommend it for all those who love their music when working out.

Received the product and earplugs fit only in 1 ear.  The sizes are limited and have to fit just right to work.  However, I found a trick that worked for me.  May not be entirely right for everyone, but I took some of my POMADE hair molding wax, and put an ever so light coat on the earplug and it sealed and fit snug.  This works best because it sticks and is stiff just like your own ear wax and doesn't slide.  Come to think of it I hardly have any ear wax in my ears so thinking maybe others who are similar may find this would work.  It would be nice if H20 would have figured out a similar solution for all those who have had the same complaint.  I've read an awful lot of them.  Maybe they need at least one non-linear person on their R&D team.
Beyond this, I think the product is solid once you get the snug fit.  I would recommend.

I have tweaked the ear pieces for two weeks and still have not reached nirvana.  I swim 4 to 5 days a week.  BUT I'm not giving up, I'll exchange out the blue ear pieces some more before I toss this item.

Great design and very light, but I have trouble getting the earbuds to seal (even with different size earbuds). The result is muffled music.

i went out and bought old style shuffle just so i could get this and listen while i swim.  the waterproffbox works, keeps the shuffle dry.  it's a bit hard to press the buttons, but if you are finger strong you can fast forward, volume up and down.  i definitely use with a cap and goggles.. the buds stay in better with cap but still bobble out my ear.  so... a little challenging, but if you only use your shuffle for swimming it's probably easier.  hook it on to your favorite goggles, be sure to turn it on before you get in water... and off when you finish... it's been easier to stay in and do laps.  When a favorite song plays it's a real treat!  i use my i-touch for all things on land.

I was skeptical of a "waterproof" audio swimming device, even after reading the great reviews. I was worried the unit would be too big and heavy on the back of my head and I didn't see the earbuds being able to stay in my ears.
All my skepticism was proven wrong. This device is simply amazing. It works wonderfully. I have had no complaints. After the first lap, you dont even notice it. Even changing volume or songs is a simple touch to the back of your head.

I highly recommend this.