Comparing US patent search engines

I quickly put together this short animoto-video showing the beta Google Patents, US Patent and Trademark Office (USPTO) and new Xyggy patent search engines, entry page followed by advanced search page. How do they compare in your view, focusing on US granted patents from 1976 onwards?

You should notice a difference with the Xyggy engine. Why? It runs an item search which it claims provides substantial advantages and additional information over text search.  Also, the makers say that with multiple items in the query, Xyggy discovers what they have in common to return better results.