I've been using this with my iPhone while kayaking and couldn't be happier. The iPhone fits perfectly inside. I keep the lanyard attached to my PFD and stick the whole thing into one of the PFD's front pockets. Its waterproof and gets wet on occasion, but I haven't seen any moisture or condensation inside. I took a hard dunk when hit by a wave but the phone was perfectly dry.
I can talk on the phone and also use it to get weather and tide info and with MotionX GPS. Overall, I don't have any issues using my iPhone through the plastic. I did drop a small silica pack on the bottom to absorb any stray moisture. Because its exposed to sea water, I rinse the outside and the top after using it and let it air dry.
My only complaint is that back is blue so I can't use the iPhone camera, but not really an issue since I also carry a waterproof Sanyo camcorder...
Colorful, lightweight, and waterproof (so far). Got mine to put a small camera or cell phone in while kayaking. It's on the small side, which is good for a compact item like a phone or camera that you want on you all the time, and the carabiner and neck loop are a good idea. Easy to use cam-lock type closure, which works, although I regard this design as more splashproof than truly waterproof, in that I don't think I'd risk submerging for extended periods. Otherwise only limited only in that this is pretty much a one-item case, so if you're looking for something to hold several items, this isn't it. It's also fairly tight for most items, so it's not really ideal for taking something in and out a lot.
Last year, while at the beach, I was knocked down by a big wave and ruined my cell phone, having to spend $100.00 to replace it. This year, me and my cell phone will be safe. Have tested it in the pool and it does what it says it will do. It's water tight and floats, which makes me very very happy.