I have gone back and forth in my opinion about this plugin.
You will clearly see faster loading pages with this plugin than with any other caching plugin (Quick Cache, WP Super Cache, W3 Total Cache etc.), including other straight up html creation plugins (Really-static, Alpha Cache).
The biggest thing to consider when using a plugin that is this aggressive in delivering html pages is that it will disable ALL dynamic processes (such as page redirects).
But the biggest annoyance to me is that you are not recognized by WordPress as being logged in when viewing any of your webpages. This means that you do not have access to the WordPress links that are normally visible at the top of the page. But more importantly, if you are using analytics, such as those that come with Jetpack, you will be recorded as a site visitor, and every page click will be recorded as a pageview.
But the results are blazingly fast and well worth the disadvantages if your are running a predominantly static website. And combine it with the Generate Cache plugin and you have a winning combination.
PS; as per virus concerns, I have run Wordfence Security with this plugin active and have not gotten any negative feedback.