When it works, it's AWESOME. I hold my breath every time I try to turn it on.
I've had this for 9 months, and I swim 2-3x/wk. Because there are so few buttons on it, it is very mysterious as to what's going on if you hit "Play" (aka "Power"---what a bad idea) and nothing happens. Adding to the confusion is the one indicator light (green) under practically opaque BLUE plastic, which makes it next to impossible to see most time (like being outside next to the lap pool). WHY????

Also, it appears to discharge itself at random in my gym bag. So every time I pull it out, I hold my breath, squint at it multiple times, and attempt to push the correct combination of buttons to make it turn on and play. When it does, I love it. Unless it stops playing while I'm swimming.

Finally, I have very few mp3 files. Because it's not able to read more than mp3's or wma's I have to go through my library and convert them....storing two versions of the same file on my harddrive. This means I never ever change the music on there. :(

I don't think there are other good options on the market right now, so this is it--better than nothing, right?

As a final note, (despite my confidence that I didn't accidentally get water in it) now it doesn't appear to be charging, recognizable by the computer, or play music. Le sigh.

Very disappointing
I agree with Karen, I was very hopeful when I got this, but it has worked for all of five minutes. The clip works well, but after loading the songs, I have never been able to use it. It is hard to use when you are in the water and it has never played for more than five minutes, which meant that all the time I put into loading songs was wasted.

For some reason, it never triggers the safely remove hardware icon, even though the computer recognizes that it is in. It looks nice, though and stays in place.

It's amazing how well they work!
I read several reviews of both this and the Speedo mp3 player, and decided to buy these. Wow! I am totally impressed!

First, I can't believe the sound conducts so well through my cheekbones. Underwater, it sounds totally amazing, and it seems loud enough that I would think others in the pool could hear it, too, but so far no one's given me any crazy looks, so I think they can't. Above water, it's not so bad. It's noticeably quieter, sure, but it's not like your music cuts off completely when your head's out of the water, which is what I was afraid of.

The headphones/cheekphones/whatever-they-are stayed in place perfectly while I was swimming freestyle, backstroke, and breaststroke, even with flip turns. With butterfly, they tipped back at an angle and started covering my ears, which made it quieter in the water and louder out of the water, but it wasn't super obnoxious, and it didn't bother me to wait until the next time I stopped to straighten them again. Full disclosure: I'm not doing more than 50 yards of butterfly at a time. If I were psychotic enough to do 500 yards of butterfly at one stretch, my decision might be different. My guess is that diving into the water would shift these puppies as well, but that's not an issue for me. And it's possible that if you tighten your goggles enough so that your eyes bug out, they would stay in place anyway. I'm not going to test that theory.

My goggles didn't leak at ALL with these clipped on. I use the basic TYR Racetech goggles, and they worked just fine.

The charging process and drag-and-drop music transfer process were remarkably simple. The only thing I thought was weird was that on mine, I didn't have three folders pre-programmed onto it for playlists. It was blank, which basically means I have one playlist. This is fine with me. I might later try to reformat the drive to see if the three playlists pop up, but I'm good for now.

I've just been getting back into the pool on a regular basis, and I'm still pathetically out of shape. With this mp3 player, it makes it much easier for me to swim longer without focusing on how tired I am. I went from 1,250 yards one day to 2,000 yards the next, mostly because I was able to be entertained enough by the music to stomach through it.

The nerd appeal of the bone conduction technology is another huge plus. It's definitely a conversation piece at the pool.

I highly recommend this mp3 player, and I'm gonna use the hell out of it.

FINIS SwiMP3
I've been using the Finis SwiMP3, along with the Aqua Spere Stationary swimmer, theFinis swimmer's snorkel and earplugs fro the local wlagreens to swim in our backyard pool all summer. The combination is PERFECTION! I know - it's a lot of equipment - but the payoff is I'm able to swim endlessly whenever it's convienent for me. I don't have to share a lane, go through a locker room, pay a membership fee, drive to the pool, stuff my work clothes in a small locker... The SwiMP# has worked very well. The buttons are sort of small and tough to find once it's attached to your goggler strap, but I trun it on shuffle before I put my goggles on and I'm good to go. I recharge it through my lap top, or plug it in to a port on my computer at work during the day - no need to spend extra money on a charger you really don't need. The sound quality is excellent with earplugs. It's really amazing. I guess I'll return to the Y this winter - I'll see how it works lap swimming with turns then.

Do NOT waste your money or time.
I have to agree with many of the prior reviewers. This product simply does not work. I also loaded many songs from itunes only to find that just a few unprotected ones played. I then emailed finis re the problem and they gave me the instructions to erase the disk and then go through a pretty complex task of unprotecting the itunes songs and then reloading the headset. Since then, NOTHING plays. I have now tried to get them to resolve this problem and they just keep giving me the run around. On top of all of this, i also concur with the other reviewers. As the unit did play for a couple of workouts, i have to say that the sound quality is very poor and the volume is very soft and tinny...even at maximum volume. And, as all have reported, if your head/ears comes out of the water (as in swimming the breast stroke) you lose sound almost completely. On these issues, i tried everything, including putting a swim cap OVER my goggles and the unit to try to keep it closer to my head. It didn't work AND looked stupid in the process :) I have now tried three different brands (speedo KILLED my ears and the H2Oaudio break very easily). I am to the point of agreeing with another reviewer--leave the mp3 experience to running and just try to go into a zen state during swimming.