JayLenochiniMac
macrumors G5
Oh man, every time I take my iPhone out of the bumper, I get nervous that it will break. It's like a slippery yet beautiful glass brick.
The glass back isn't any more slippery than the plastic back, and is in fact less slippery than the aluminum back of the original iPhone. Although I realize you mean you can grip it better with the bumper on.