You may often hear that Drupal is hard to learn.. well, a few years ago may be true, but now all has changed, many improvements were made so that Drupal is not as difficult as before. Moreover, the community has released version 7.x that focus on user experience, user friendly administrations is one of the biggest weaknesses of previous versions of Drupal.
Why Drupal is so special? because Drupal is open sources, robust, flexible, and developed by hundreds of thousands of people from all over the world. Drupal also used by many of the most influential sites on Earth, I only mention on Earth since I have not had enough evidence if Drupal is also used on other planet. :)
To learn more about Drupal, you can visit about page that explains one by one the main features of Drupal, don't forget to read the get started page, and read the documentation page if you lost somewhere.