With the introduction of material design, the looks of Android apps will finally mature. They can compete very well with iOS designs. Android material apps have a flat design, but come with some interesting differences such as elevations. Consider the following figure for example:
Think of it as multiple slides of paper. It is based on, well, materials. Each slide of paper has a particular elevation. So, the environment is in fact a 3D world with effects such as light and shadow. Any motion should have real-world behaviour as if the moved elements are real physical objects. Animation is another important element of material design.
First have a look at https://www.google.co.in/design/spec/material-design/introduction.html to see what material design is all about. Sure, many things are interesting for designers in particular, and you probably are interested only in the implementation of all this beautiful stuff; however, this link provides you with a little bit more context about...