So, you have nice home screen that looks Supercool! But how much of your time is spent on the home screen? Lockscreen? Adding on to the fact that the number of apps that actually support the "complete" themes is very few. This is why Apple Refuses to add theming to its device. It makes no sense. All it does is slow down your device. Think about it, would you rather have a nice speedy device? Or a slow 'cool' looking device? Sure you can show off to your friends, but in the end, its functionality over aesthetics.