I don't own a Prius, but I've spent a little bit of time in one. With 3 full grown American males inside (175lbs-200+ (me) each) driving at highway speeds at altitudes between 5,000 and 8,000 feet I saw it return an honest 46mpg. That's not 60mpg, but it's a far sight better than the 16 my 4runner returns, and I would be interested to see what a Fit would do with 3 people in it at those elevations and speed.
I found it to be quite comfortable, even in back for my 6' frame, and I'm enough of a geek to really enjoy watching the little TV tell you how much fuel/electricity your using or generating.
I agree that if you're looking for "bang for the buck" a low mileage used Jetta TDI would probably be a better choice, but the hybrid technology is not entirely useless.
I would also guess that the estimate of $5k to replace the batteries is a bit low. I was in the wating room at a Ford dealer recently and overheard a customer complain about the $8k bill for new batteries in his Escape hybrid. That's steep.
This was probably no help, but that's what I know.
-Matt