One particularly nice feature of the new version: gpg-agent no longer just stores the passphrase and hands it out to gnupg. Instead, gpg-agent actually holds the private keys and does crypto operations with them, and never lets any other process have the private keys or the passphrase (other than the pinentry program that prompts for the passphrase).
See https://gnupg.org/faq/whats-new-in-2.1.html#nosecring