i tested it..its slower than Google actually..when i made search for Apple IPhone 4, google did it in 3 secs while mightbuy took 6 secs that too might buy provided only 5 results while google gave a lot many...
When I googled Apple Iphone 4, google still wins, as one of their ads shows me a iphone 4 with a price.
But for some more unique brands, something more interesting, often it takes a browse into the site to get an image and price. Google will always get initial results faster.