Differences from Behat/Symfony2Extension
Contexts as services
In Behat/Symfony2Extension the dependencies of a context are defined in the Behat configuration file. In this extension, contexts are defined as services - this makes reusing suites effortless, also allowing to support autowiring and autoconfiguration.
The Mink driver provided with this extension differs from the one provided with Behat/Symfony2Extension, as it uses an isolated application kernel instance, so that services state changes within your contexts does not affect the driver results. With that limitation, changing the driver to a different one is seamless. For more information, look at this issue.