The free version of the plugin works fine. I guess the other 1 star reviewer was just not sure how to find the plugin's menu? (Its in SEO -> NS Custom Analysis)
The plugin did exactly what it said it would. No bells and whistles, it just added (up to) 3 custom fields for the yoast WordPress SEO plugin to look at in addition to the_content().
Five stars for the free version.
The Pro version of this plugin is a big improvement over the free version. However, in my opinion $23 is really steep for what the plugin does. Overall it works well and does what it says it will do, but it is overpriced.. especially considering the WordPress SEO plugin itself is free.