Not to be confused with Panda the animal the update refers to the man behind recent algorithmic changes. The update is named after Navneet Panda the chief architect of recent changes. This way best seo practices have been further strengthened.
As I have been always saying the impetus on SERPs lies on quality site building. This does not mean standard optimization practices have been done away with. The paradigm has changed, it is good quality site first. A website for users and not overtly manipulated for search engines.
Look deeper into the site especially the design part like download speed, user friendliness, contents etc. Scraper sites or those made for Ads were completely wiped out leaving few that offer good information. Those who relied on content picked up from other sites by intent and habit have suffered the most. The sites have been pushed down deep or eliminated from the SERPs. The Panda update has pushed the seo professional more towards understanding web design and contents though he may not be a designer.
Dig deeper in the analytic in order to discover how visitors treat your site. Do they find information they are seeking and easily? This depends upon content creation and link architecture and your analytic will display the time spent on your website. This is called the bounce rate and it tells the search engines how much time has been spent on site - the more the merrier.