Users appreciate the Mailgun plugin for its ease of setup and reliable integration with WordPress, allowing seamless email sending through Mailgun's service. It is particularly valued for solving email deliverability issues, integrating well with various contact forms, and providing free email quotas. Users also mention its efficiency for agencies managing multiple sites. However, the plugin has notable drawbacks, including outdated updates, slow support response, usability issues with specific configurations (e.g., Multisite), lack of logging features, and concerns about bug fixes. Errors on updates and a perceived decline in maintenance and support add to user frustration. Overall, while functional, the plugin's maintenance and support need improvement.