Yes it does but it's a choice. You can either have the button covered of not. I like it because it shows the silver of my phone through gaps of black
That would just be a killer for me... I guess the back adds (main part) adds grip and looks flashy... But I dont even see why they would make the part for the button if it takes away the functionality of a major part.. I couldn't live without finger print sensor, so useful and fast.
EDIT: also the front piece obscures the small glass to ally edge, would piss me off when sliding.