I am using this plugin and loving it. Replaced the use of various other plugins.
A bug/issue that I've found is that if you use it on pages, and select the show thumbnails option, it always shows the ugly default image, since most pages don't have a featured image. (and not all themes support it)
All my posts have default images, but none of my pages. So it looks good on posts, BUT TERRIBLE on pages if you use thumbnails.
The plugin should use an image from the page, if no featured image is found.
Other plugins in the category already do this, and I feel that it is a critical feature that needs to be looked at.