Worth it? Depends on what you want.
For ~$10 it provides possibly the highest amount of content-to-cost your likely to find on any current title.
The maker actually pointed out in a few interviews that "feature creep" set in, and they really didn't want to change the price point even so.
Main thing it adds is a new research tree to boost defense functionality, add starbases.
Unfortunately, I haven't had enough time to play it, and I've owned it since early beta.
I do enjoy it, what little I get to play it, but if you enjoy rushes, this will likely make rushes... a bit harder, especially in large games.
Simply my own opinion, and your mileage may vary.
Back to lurk mode.
wow 10 dollers not bad for expansion pack, i thought it was going to be 20. is it in stores?
I believe that you can buy it at a retail store as well. I'm not sure. because theirs a box art shot somewere i saw and it had everything in it, manuel, code, etc. Whatever it comes with it looked real. But i'm not sure.
You are able to order it from Stardock and they will ship you the box.