Rogerio,
I think it is an excellent book if you already know
Java and would like to learn Android as a beginer.
So the pre-requisites are clearly just
a) Java
b) Eclipse
IDE
Given those two the 1100 pages of Pro Android3 takes you concept by concept (the way I and Dave learned) and API by API and develop simple projects that demonstrate those concepts.
Our focus audience are
a) java programmers but beginers for Android
b) Intermediate to Advanced to Android programmers
it will start you slow but also gradually ask you very fundamental questions on the behavior of Android (especially its multi-threading model of programming).
What helps you if you are a beginer are
a) Good coverage of basic fundamental concepts: intents, resources, content providers, dialogs, menus, controls (25% of the book)
b) Process and threading model: threads, components, handlers, receivers, long running services (25% of the book)
c) Advanced APIs that are explored chapter by chapter: animation, opengl, touch, sensors, text to speech, search, contacts, widgets, live folders, 3.0 fragements, framgment dialolgs, drag and drop, action bar (50%)
Especially the menus and controls chapters gives you the very basics of a workable application.
what helps you to take you to the next level are "b" and "c" above.
Three authors spent over 2 and 1/2 years to write teh book and we wrote as we learned and discovered and fumbled. Hopefully the hardknocks are remembered adn documented.
See if this is helpful..
Satya