This thing was a godsend for our cruise to the Bahamas. Since you have to pretty much leave anything you bring off the ship on the beach, we absolutely needed something to keep our IDs and cash in to take into the water with us. This thing kept everything inside absolutely dry, and although initially I was annoyed by its moderate size, it really came handy as we jammed more and more stuff in over the days (including a cell phone).
The bottom line is it was definitely worth the $6.99 we paid; Also, just FYI, it's normal for the ziploc folds to get wet; the stuff inside will be dry though!
The dimensions listed are deceiving. The description says 11 x 7 x 3 inches. The acutal dimensions are 10 long x 4 3/4 wide x 3 deep, including the material that's rolled up for the seals. The acutal the usable space inside the pouch once sealed is about 6 x 3.5 x 3 inches. If you're expecting to store much more than a small camera or wallet, keys, change, etc., you'll be disappointed.
This bag works perfectly under water. I used it several times under water with my camera and never had a drop inside after opening. The only reason I gave it 4/5 is that I have the same camera shown in the product picture and it was tough at times to get my camera to turn on and extend the lens. It would almost make it but then close after sensing tension. It was tricky at times, but I was still able to get my camera turned on. I'd highly recommend this or its bigger brother to anyone needing to keep something dry under water.