Unfortunately, you CANNOT customize the background color nor the font color despite there being options for in the settings. Which means if you aren't using a theme with a light background where this plugin will be, it will look horrible.
Looks like several people are having the same issue (another user posted about this on the author's site itself)...but there is no fix.
If customization is actually allowed, then the option for it should simply not exist.
Due to the lack of actual customization and lack of support on this issue, it's worth 2 stars to me (because it's extremely limited for those of us with customized themes).
I'll re-rate if this ever gets fixed, but I'll be looking for an alternative plugin in the meantime.
*** EDIT: 9/27/2013 ***
Sorry it took so long to update this review. But the current version is indeed fixed, it is customizable from the cp, and works perfectly. As such, I've given this review 5/5 reviews.