I know two Porsche afficionados who have driven the Panamera, and they both say it's the nicest ride they've ever seen. It'll be interesting to see how it does, because most marketing experts will say it's a mistake. Just look at GM and how it's tried to make every one of its brands everything to everyone. Now they're nothing to everyone.
One of the people I know owns over 50 high performance autos, including a Bentley, a Ford GT40, a Porsche Carrera, and a Mercedes SL63 AMG, and he says the Panamera blew them all away. If anyone could pull off a 4-door sports car, it's Porsche.