I'm using the all black mophie juice pack plus, almost 7months now. I never remove the phone from the case as I love the size of it and touch feels of the case, plus the fact that I know that my phone will survive if it falls down ease my mind and I do not worry about the iPhone to drop, it actually dropped several time already and thanks to mophie which took care of the impacts. The battery is about 110% of the iPhone battery and yes, the sound is changing when you have the iPhone in the case and I like that sound much better. I give it 10/10 for everything this case is doing for me and for my iPhone 4S