You can easily change the appearance of the Minecraft PE world using textures and shaders. Textures only slightly alter the look of the content, while shaders make it as realistic as possible. Your world gets new shades, animations, and lighting. Shaders will create realistic water, proper shadows from the sun, and correct animation of swaying leaves. Not all devices may be able to handle large shaders, but even for weaker devices, you can find your own improvement for the MCPE world.