[pm90]

Effective Go is a great intro: https://golang.org/doc/effective_go.html

Also, check out the blog posts for more information on specific topics: http://blog.golang.org/. They are really well written.

[andmarios]

^ This! It is one of the reasons I like Go. Effective Go is all you need to understand the language and be able to read even the most complex Go programs.