It is a good plugin. Unfortunately it seems it was written by someone not speaking any inflectional language, nor any other language with diacritical characters. I also noticed og.image is completely broken, this disqualifies this plugin for any SEO things.
I speak several languages, one of my sites is in Polish, which is one of slavic languages, which is highly inflectional. This plugin doesn't support diacritical characters in the keyword - it gets lost, it says my article doesn't contain any appearance of the keyword, but then it says my keyword is in the first paragraph. Also it doesn't know that my article and/or its title and meta contain the keyword, but not it its basic form, but in its flexed form.
Google however is very good in understanding and recognizing inflection languages and its search finds different forms of the word.
Not sure how you could fix it with your plugin, but something as the 'core' of the word would help. Please check https://en.wikipedia.org/wiki/Inflection and the example with the cats. The plugin could know that all words starting with "gat" are the keywords if "gato" is defined as the main keyword.
I also don't understand why it doesn't contain Google Analytics code, while All-in-one SEO does. I know Yoast has a separate plugin for that, but why multiply?
My site imports image from wikipedia. My article imports image:
and displays it correctly. But what does this plugin do?
It sets og.image to:
Meta Tag <meta property="og:image" content="http://paleosmak.pl//upload.wikimedia.org/wikipedia/commons/thumb/8/8b/Kidney_beans.jpg/512px-Kidney_beans.jpg" />
Completely broken, waste of time. They only want to make money, they are not interested in other users. Avoid.