You can easily change the look of the Minecraft PE world with textures and shaders. Textures only slightly change the look of the content, while shaders make it as realistic as possible. Your world gets new hues, animations, and lighting. Shaders will make realistic water, real sun shadows, and proper leaf ripple animation. Not all devices will be able to work with large shaders, but even for weaker devices you can find your own world improvement in MCPE.