InDesign ExtendScript...is this worth learning?

Hello,

I have been trying to learn AppleScripting so that I might automate more of my of my InDesign stuff. When searching for more books, I came across a book by Shirley W.Hopkins called automating Adobe InDesign CS4 with ExtendScript. Does this scripting option seem to be a good one to learn, even over AppleScripting? It seems like a valuable option if I want to focus on InDesign, but I would like to hear from others if they are using it and is it worth the learning curve?

thanks!!

babs