The animation in Android 5 has a flow that developers should be using to bring and guide their users on how-to use the application. The flow should feel normal while going through the different areas of an application.
Using a proper implementation of UI and UX designs is what will contribute to make an enjoyable experience for a user.
The elements of an app visually needs to make sense, there needs to be a flow, it needs to be intuitive for the person using it. Motion design is here to help you to guide these users.
There's currently plenty of applications out there that are very easy to use, the flow is continuous, normal as if it was intuitive and users don't even realize that they are being guided.
An example of that is Google's Inbox application; clicking on an email expands the view to allow the content to be seen, also called activity transition that seamlessly guides you. This can also be said of the Google Movie app, pressing on a title would subject it to a transition that would take the cover of the movie bring it forward to then resize it to a smaller mid section location allowing the displayed movie banner and synopsis to be revealed.
You also have some examples of bad UX implementation and in this case Facebook was one of those examples. The infamous back button on the applications doesn't always do what we would expect. The scenario revolves around going to friend's profile page and looking stuff up. While doing that you decide to do a search while still being on your friends profile page. You'll end up with the results from your search, but didn't find what you wanted, then you'd hit the back button just to be brought back to your news feed. Wouldn't you think you should be going back to your friend's profile as this was the last known location before the search?
Properly implementing the UI and UX of an application helps not only you, but your users. Providing the best experience you can will help ensure a lasting user base.