I just completed the Android App Components - Intents, Activities, and Broadcast Receivers MOOC taught by Vanderbilt University on Cousera. Since I did pay $49 for the course, I'd like to share my thoughts.
This is definitely a useful class. I think if you plan to be an Android developer, its important to understand the intricacies of the architecture and structure of apps. I was disappointed by the fact that there were no mandatory programming assignments. Also, beyond the normal instructional videos, there were a lot of videos on code walk-throughs. After a certain point my brain just shut down.
Will you learn how to program Android with this class alone? Absolutely not. Will it explain how to app screens communicate with services and other screens? Yes. Will you be able to implement real Android apps without other courses/education? No.
This class is part of the Android App Development Specialization. I think you need to take most of these classes before you can really start Android development. Is this MOOC worth $49? Yes, only if you plan to complete the whole specialization.
OBTW, I did find out that Udacity has an interesting single MOOC course on Android development. It would have probably made more sense to try that first before going down this more academic route.