I read a lot of positive reviews, but it doesn't show any related posts as I wanted. This is only the downside of the plugin. Option changes aren't instant and is stressful to wait for many days until the plugin starts to output related posts (or not in my case). I also used Experiments addon, and flushed cache, but it kept showing "no related posts" although I know there must be related posts with the same category and tag.
With respect to developer's work, but it's better to manually set related posts than using this plugin after all. Or maybe this plugin should offer such function, then I'm sure a lot of WP users get more benefit of using this plugin, I'd use it as I like Yarpp.