I just purchased the new 2010 3rd Gen. Prius to 'compliment' my 2007 Tundra DC 4.7 Limited.
I waited for the 3rd gen specifically for the rumored improvements, some of which appeared, others didn't ( Lit ion batteries)

The best feature so far is the three modes EV, Eco and best... Speed !
This mode can be accessed at any point (xcept reverse...) to allow a 'formidable' kick in the pants acceleration. I found this especially useful when accelerating onto the Dan Ryan in the midst of steel hauling semis, and lived to tell about it ! once you get to a comfortable speed and position in traffic, just hit the Eco button and resume constant speed economy mode....vast difference from previous Priu-i...

The EV mode is interesting as well, previously only available in Europe and Asia, I usually hit the button as I turn off the main artery and follow my hilly curvy road to my home, a distance of 1/4 mile up a steep hill and finally a 30% grade up my driveway...all on Electric !!!