I've driven a regular Prius from the car pool at work, and I found it slow. I'd hate to think of this one, which is bigger, loaded up with a family's luggage for a weekend away. That would be painfully slow. That poor little engine would be working so hard to pull around the extra weight, I'm guessing the FE wouldn't be that great.
A Prius V with the conventional 2.4l power train from the Camry would make for a very interesting competitor to the Mazda 5, Rondo, and Orlando.