OK! This plugin I use for more than 4 years on different web sites and it saves a lot of time for webmaster by allowing website optimization in few steps, by using this together with Joomla! default settings. It automate job of web master by adding automatically keywords, The only one reason I get 4 star to author is canonical settings in this plugin that could be very dangerous when it comes to SEO. I suggest author to improve canonical settings, because for now by following constructor description this plugin cause some importan error.
If you activate canonical tag in this plugin as author suggested with entering URL like this http://www.example.com main pages is not indexable that show a lot of seo software analysis tools, for example seo doctor, but all other pages are have properly set canonical tag. If I correct error and enter URL like this, full path, http://www.example.com/ then main page is OK, but all other pages are not indexable because their URL get one more slash /. And page, for example about-us, look like this www.mydomain.com//about-us.
I hope that autor will consider these changes and publish new plugin with properly set canonical tag, or to exclude that option from the plugin. Plugin is free, I appreciate this, but if this has serious error like this, than free can cost much more when judges come to crawl website, for example google bot, ect.