Short version: Requires iOS 6! You will get the iPhone 5 camera UI on iPhone 4/4S.
A long time ago on an internet page world far, far away, a reddit user (forgot name, but thank you!) requested why there was never been made a tweak which changes the iOS 6 Camera UI on iPhone 4 and 4S to the UI Apple used for the iPhone 5. This is, due to the different screen sizes, crafted completely different. I assume it should also have been the default 4/4S UI but they did not choose it because there would have not been enough screen size left for the camera itself. Anyways, i Google-ed around a bit and found out the fact that there is indeed a huge difference and that the iPhone 5's UI is much more beautiful. So i sat down a day (or two) and implemented the UI for the iPhone 4 (and 4S, but not tested). So here you go: 4camera and its complete source code!
You are welcome, H6nry :)