I like Drupal a lot. It's a great system, easy to set up and use, and the most important thing, there are plenty of modules, which provide additional functionality. However, every time the Drupal development team release a new major version, the module authors have to change their modules in order to adopt to the new platform. This is a major drawback, because it is a considerable obstacle for those, wishing to migrate to the new version. Module authors are often busy and it takes considerable time for them to make the necessary changes.