I bought this for a relatively new Garmin Edge 530 in order to hit the free shipping threshold. It's nicely made and it's reasonably priced. At the time, I hadn't owned my Edge very long and imagined that this would be a good thing to have in case I ever dropped the Edge or it came loose from the mount. I would imagine that if you're mounting/dismounting the Edge repeatedly mid-ride that this would be useful protection, but as an out-and-back fitness rider I haven't needed it.
I just bought this case today and I love it. Adds the perfect amount of thickness and protection to the device without rendering it unusable. My Garmin felt naked and I was terrified of dropping and damaging it. Its super easy to put on, and once its on the device, it fits tightly and doesnt feel squishy or like its going to slip off. Probably going to get a few more in other colors.