Ok. I need to use Intellij to its full functionality and I want to buy this book: IntelliJ IDEA in Action
The last version of Intellij is v8 (v9 very soon), but the book presents the v5. Is it a good idea to buy the book?
What are my alternatives (beside the Help feature)?
Unless you are new to software development, I wouldn't buy an IDE book. I would go to the help menu and walk through the tips, and also print out the default key map (also found on the help menu) and try the various keystrokes. I would pay attention most to the keystrokes for items on the GoTo, Code, and Refactor menus, as I use those all the time. Also, learning the various "live templates" is useful. You should also tie IntelliJ into your version control tool, having buttons and shortcuts to it inside your IDE saves time.
If you buy the book, most of the tips and keystrokes should be the same. I've used IntelliJ since v4 and the most-used ones have pretty much stayed constant. Unfortunately (for book buyers) much of the configuration of IntelliJ and of IntelliJ projects has changed significantly so the book might show screens that no longer exist.
I found a good source of tips on how to use the IDE on the IntelliJ blog at: http://blogs.jetbrains.com/idea/ they are listing the new features of the upcoming MAIA version plus they are also listing some productive ways to do certains operation. Also take a look at this video
There is also this video on youtube that is giving some productivity tips on how to use keyb shortcuts.
I read the book from Manning and I found there a really good overview of the IDE. It's referring to version 5 but the genereal philosophy of the IDE is still the same. Since it is outdated, Amazon show new books for sale for less than 1 dollar so it won't harm.
There is a great 7-page ref card with lots of tips on how to use Intellij IDEA here.
Browsing questions tagged with "intellij-idea" here at StackOverflow can also be helpful. For example the following questions: