Support is really responsive. This is the only plugin I've found that correctly implements the directive, so that the price displayed is the lowest in the period that precedes the promotion. Code is very short and well written, which helps making sure that it works correctly with minimal impact. Which cannot be said about the other plugins I've checked.
It doesn't have useless options (ie options that break the EU directive) like other plugins that were developed earlier.
I've tried wpdesk and Omnibus — show the lowest price.