As you may know, Brad Geddes is one of the world's leading authorities on Google Adwords.
I saw his one day presentation in Sydney yesterday. He's just released the third edition of his Advanced Google Adwords book... which I found clear and simple... given it was also comprehensive.
A useful outline of key Adwords topics & updates on them are in this blog post at his blog... which is also worth following. http://bit.ly/1gGgbhi