However, I do mostly highway driving and still get 50mpg. (Unless I am doing a rapid acceleration, it seems to be using a combination of the gas engine and the battery.) The gas efficiency is apparent at the pump - a $20 fillerup yields upwards of 375 miles.
I think it's worth it... but that's just my opinion.
(Mec, when I was car shopping, the Prius wasn't that much more than any other car I was looking for...)