Omega is created to be a robust and extensive base theme. It can be as much or as little as you want it to be. In order to get the most out of it there are some basic setup steps we recommend you take. These are just recommendations however, Omega will work right out of the box without any modification to your system.
If you’re upgrading from 3.x be sure to look at the 3.x vs. 4.x chart to see how your process will change (and even improve!). Next you’ll also find recommendations for Drupal modules and external programs that will make your life much easier.