10 points for functionality and information offered, 0 for overall effect on the rest of the site.
First case: front-panel still working, admin panel inaccessible. It started with not being able to access pages I wanted to edit; few days later I could see the login page, but I couldn't login, and now I have a big blank screen instead of login page. The effect is strangely gradual, nonetheless annoying. And now I will have to reinstall WordPress again and take it all from the begining.
Second case: "Error establihing a database connection". This is the message I got when I opened my site this morning. Once I deleted the plugin, it started working again. Still I have a forefeeling that soon I will have to reinstall this one, too.