I think this works well if you're already invested in GPG for code signing or something and use terminals a lot. It's a little unusual as key management uses asymmetric crypto, so you can add a password without opening your keyring. The passwords are stored in directories and the directory names are the plaintext name of the password (i.e. the site and username). So it doesn't offer privacy. Tampering is possible, you can delete a password without unlocking the keychain by deleting the directory. So it only really protects read access to a password.