Google has released the user guide for Android’s latest version 2.3 aka Gingerbread. This user guide includes Android Basics, features details, how to do stuff on your Android phone and more.
If you are migrating from another OS to Android, and feel skeptical about Android usability, you can go through this guide to get all the needed information.
This user guide will also be helpful at times when you get struck using some feature of Android.
Download or view the full guide here.