Not a case for everyday use, it's far too large to carry comfortably in most situations. However, there are situations when this case works out very well. I spend a lot of time kayaking, and this case is perfect for being out on the water, when used with some water resistant headphones. I wouldn't go swimming with it, but it's survived all of the splashes and minor soakings it's received while out on the kayak. The clip is pretty convenient, I just clip it to my vest or shorts, and no worries whenever a swell gives a bit of a splash.
I use the case with a 2nd Gen iPod Touch, which fits easily and securely into the case. Because of the foam inserts in the front of the case, it will also fit other similar-sized electronics, even if they're a bit thicker. I have a G1 phone, and it fits right in as well. As with all Pelican cases, it's very sturdy, and I have no doubts I could throw my iPod at a wall, drop it on the ground, sit on it, maybe even stand on it with no damage.
Only problem is that you cannot operate the iPod whenever the case is closed. If you have a good music list, it's not really a problem, and as long as you're relatively dry, it only takes a moment to open the front and do what you need to.