The short answer is yes, WooCommerce payment is secure. Since WooCommerce is built on WordPress, you can rest assured that a WooCommerce site is as secure as any WordPress installation. Make sure you keep your WooCommerce site up to date so the security features are the latest available. To be extra safe, only buy WooCommerce-related plugins so you know that their code is trustworthy. WooCommerce has made it very clear that they stand behind their products and are staking their reputation on their security.