We did a mixed breed analysis from Wisdom MX as part of thier initial study with the Vet Clinic I was working at at the time. It was done before they released the tests to the public. Here is my Abigail's results, and a picture of Abby (the little brown girl next to our Pyr Ollie). So you can get an idea of what to expect.
Based on Abigail's behavior and appearance I believe this analysis. However, some people got bizarre results. Like a dog who looked like an apricot poodle/bichon frise mix came back as a rat terrier husky mix...
27% Australian Shepherd, 25% Rough Coated Collie
Small percentage St. Bernard, West Highland White Terrier
--the packet comes with a brief breed description of the major breeds of dog they determine your dog to be a mix of as well-- http://s147.photobucket.com/albums/r295/ladespidapoeta/?action=view¤t=abigailDNA.jpg
Here's a link so you can see it full size