If you have a sim pin, then you get the default enter pin screen, for me it is ugly, Google could have done a better job. So I a played a bit with the screens I came up with two designs, let me know if you like them?
Black backgound, landscape
Black backgound, portrait
Transparent backgound, landscape
Transparent backgound, portrait
Current Devices: Sony Xperia Tablet Z LTE (SGP321) | LG G2 (D802)
NOTICE: I do not respond to tech support questions through PM. Ask in forums, everybody will benefit