This is my second Bone armband now. I bought the first for my 3Gs and now this one for the 4s. It sits tight and snug to your arm and the lack of a plastic front cover makes it easy to use. You do have to stretch the material to get the phone in and out but the first one I bought never weakened. It was only after the strap broke that I had to replace it but I got about 2 years use from it.
I would not take any armband out in the rain as I wouldn't trust any with a plastic front cover to keep my phone dry, so the lack of a cover is not a negative for me. When running in the rain I prefer to trust the inner pocket of a rain proof running jacket.
The armband that I was sent did not match the picture on Amazon however. It is a darker blue and orange (which was the same as the first one I bought for the 3Gs). It still looks good but for me the misleading photo drops the product 1 star.