Since PGPdaemon does not require the passphrase to be stored in an environment variable, it should be considerably more secure than automatic decryption methods which use that technique. PGPdaemon make a good effort to avoid being compromised. Future versions will provide various features to detect and thwart attempts at tampering. A simple filter programme which reads in encrypted data and writes out the decrypted version. It uses PGPdaemon to do the decryption.
More information See the manual pages and the files in the doc directory.
Well worth reading. See the GNU General Public License for more details.