Google developed Android to be an open source platform, so by it’s nature it can be customized.
So if we talk about mobile OEM’s [original equipment manufacturer] like Samsung, HTC, Motorola or LG they just can’t leave Android alone. They customize the Android version for their set of devices. Samsung’s Touch Wiz, Motorola’s Moto Blur, HTC’s Sense are some of the examples.
How it is impacts on already developed app? Will it work fine?