It takes long take to understand all Opengl pipelines because of mathematics and the shaders.
Apparently for your case, It can be the best book (http://www.amazon.com/iPhone-Programming-Developing-Graphical-Applications/dp/0596804822/ref=sr_1_1?ie=UTF8&qid=1392851323&sr=8-1&keywords=opengl+es+iphone+3d)
because the book always compare opengl es 2.0 to es 1.1 and also supports many codes.
And Second choice can be looking the game engines especially oolong engine shows very well how to use opengl es 2.0