This is a greta idea and works well but I have had two and both times they have failed. Yep sure they were dropped but the design should be able to more robust than that. The USB charging jack has failed twice and it just dies....not good enough, I have given up.
I am super cautious with my phones. I had this 40 days and it will no longer take a charge. The case looks and feels great but it is strictly an extra battery. It is not protective as it cannot survive a drop. It is nice when it works - but it was just 40 days for me.