Quite secure, but in the field of security there is always room for improvement of security, at the cost of compatibility and ease of use. I would at the very least recommend you look at securing root account if necessary, securing openvpn account, and reviewing your HTTPS cipher suite string, and installing a valid SSL certificate.
See our security recommendations page;
https://docs.openvpn.net/getting-started/recommendations-to-improve-security-after-installation/