First off, I thought this plugin was great ... until it broke my site. Don't know what snapped, I hadn't done anything like update the plugin, or update my WP version, or anything else, but suddenly my site just went down. Troubleshooting determined the culprit was Tweetable. I confirmed this on two different WP installations on two domains - Tweetable crashed my site. After deactivating, the sites work fine. Upon attempting to reactivate, it failed due to a "fatal error".
So as it's now unusable, I have to give my thumbs down to the plugin. Too bad.