Obfuscation gives you better protection against reverse engineering. It makes it harder for those decompiling your code to understand it.
That said, you should know there is no way to completely secure your app against decompilation. It is just a matter of how much time a person is willing to spend on cracking your app and how good he is.
If you want to protect the logic of the app you should probably move that code on a server and use api calls to exchange data between the app and the server.