The plugin is great for its intended purpose. We uploaded the wrong filetype, set a support ticket, and received a response within a few minutes. Couldn't be more pleased with both the functionality and the support!
It is easy to use: simply create a new module from the Module Manager and be sure to choose "Joomla 1.5 HTML Module" as the module type. Now insert your custom HTML, enable and publish it, and you are good to go.