The document discusses new features and changes in Puppet 4, including Puppet Server running on JVM, packaging improvements, environment configuration options, language features like lambdas and HEREDOC support, type validation, and deprecations like node inheritance and hyphens in names. It highlights four key powers of Puppet 4: performance, scalability, measurability, and flexibility in dealing with complex data types natively. Upgrading to Puppet 4 requires changes to comply with deprecations and testing to ensure compatibility.