While it includes many features, the plugin has certain issues:
Searching: The Wiki article presented is the same page as would be returned by using Google's "I'm feeling lucky" limited within the Wikipedia website. Searches will typically show certain specific articles instead of the more useful disambiguation pages, sometimes even showing trivial articles in place of more substantial ones. (It may be possible to weight search results toward disambiguation pages by adding the term "disambiguation" to each search).
Linking: Redlinks (Wikipedia links for which no article yet exists) link to the "edit" page, instead of the default Google search term. By default, anonymous article creation is not allowed.
If a user is set to login by default into Wikipedia and the user has an alternative theme set in Wikipedia, the display of the Wikipedia section of the search does not render correctly.
When searching for something which (usually unintentionally) results in a large Wikipedia page, the entire web browser may occasionally lock up while downloading the article.
Speed: loading the Wikipedia page can slow down the loading of search page.