Today I got into a discussion about Symfony CMF. The discussion started with the question, if Symfony CMF isn't trying to create a solution for a problem that doesn't exists. That person thought CMF only solved a developers problem, but couldn't solve the problems for front-end developers or editors (or even added more problems). It came down to it, that he had seen the admin interfaces that come with Symfony CMF and saw that it was... less from perfect (to put it nice).
Goals of Symfony CMF
Symfony CMF aims to provide a toolbox to create your own custom CMS, not by reinventing the wheel, but by reusing existing code and sharing the produced code (parts of it will be used in Drupal 8). It aims to make it easier for developers to add CMS functionality to applications built on Symfony 2.
To do that, they looked at other solutions, solutions not limited to PHP, to structure content. This because a CMS has mostly unstructured data, and forcing this into a RDBMS isn't always a good fit. Graph database are a better fit. They found JCR, a Java specification that deals with content. They ported that to PHP and called it PHPCR; PHP Content Repository. With PHPCR, there is an API to interface with your content repository.
What is doesn't solve
Althought Symfony CMF does provide some basic admin interfaces (with Sonata Admin), it isn't meant as an end product. For most customers and editors, those screens just won't be enough. But there is nothing to stop you from developing your own admin screens that does fit you customers needs.
Symfony CMF isn't a solution aimed at the end-user, that is still you job as a developer, to implement a solution that helps your end-user and the editors. Symfony CMF just helps you to not get a panic attack when somebody tells you to add content management to your Symfony2 application.
For more information about Symfony CMF, check the bigger picture slides