A lot of people are asking themselves what are the benefits of an Android Certification. I was like you not so long ago. Now that I got it, I can tell you what they are.
First, it's always a nice thing when you can show off and say you are part of the Associate Android Developer (AAD) Community ! Why ? Because it means your skills as an Android developer are recognized by Google. Isn't that a great feeling ?
Secondly, even if I have some years of experience in the development of Android apps, I still learned quite a few things from the Udacity videos while I was studying. Some interesting things I learned:
... And so many other tricks which can be very useful.
Another advantage of being certified ? It's a plus on your resume. For an employer or a company, having a developer with a certification gives a better visibility.
So go for it ! Take your chances (here), you will not regret it ! Good luck.