When comparing Official Android developer's guide vs Udacity, the Slant community recommends Udacity for most people. In the question“What are the best resources to learn Android development?” Udacity is ranked 1st while Official Android developer's guide is ranked 6th.
Ranked in these QuestionsQuestion Ranking
Pro Best source for the most up-to-date information
The guides are actively maintained as they are the official guides for Android.
Available online for free.
Pro Covers both beginner and advanced topics
Pro Courses taught by industry professionals
Pro All courses are self-paced
Courses are always made available which means there is no waiting for the specific course you want to run. You can work through the courses as fast or as slow as you want.
Pro Offers Nanodegrees
Udacity offers a few different Nanodegrees which provide access to various different courses, project reviews and coaching support for $200/month.
Current options include Front End Web Developer, Data Analyst and Android Developer. See the full list here.
Pro Courses are easy to understand
Pro Actual feedback on coding projects
You get actual feedback from developers on your code, which is useful. Yes having your sites/apps do what it is supposed to do is important, but you need feedback to learn industry standards/best practices and other gotchas that are much harder to learn on your own.
Con Requires some programming experience
The guide is much better suited for those who have programming experience.
Con Nanodegrees are expensive
Udacity is quite expensive at $200/month if you want to do a nanodegree.