Just some notes/links about this CMS. Acquia is the main company providing end to end support of Drupal. The small business and web community always compares Drupal with WordPress, but their focus is Web Content Management for companies.
Strengths:
- Content Management Framework (CMF), not just a CMS.
- Security.
- Scalability.
Weaknesses:
- It’s a frameworks for programmers, you need development knowledge. The adoption curve is more difficult than with WordPress or Joomla.
- Community of users, developers, plug-ins, themes are more limited than other open source solutions. You need a partner to implement Drupal.
This is a deep analysis comparing: WordPress Vs. Drupal.
There is a huge difference between v6x and v7x, but there’s not too much.