Users appreciate the Retainful plugin for its user-friendly interface and exceptional support team. They highlight its effectiveness in recovering abandoned carts and boosting sales through automation and customizable features like pop-ups and email notifications. The support team, particularly individuals like Mr. Krishnan and Ram, are noted for their prompt and thorough assistance, often willing to schedule Zoom calls for issues. Users also value the plugin's ability to handle processing on its servers, reducing website load. However, some drawbacks include occasional sync issues with carts and aggressive renewal payment reminders. Despite these, the plugin is well-regarded for its overall functionality and customer support.