We bought a used Prius less than a year ago based on these glowing reports of battery life. We just got back from a 2 week vacation, during which our Prius sat un used. Now we have all kinds of warning lights and the dealer says it needs a new HV battery pack. Cost estimate $3000.
It's a 2001 and we're told it was commissioned in March so our 8 years is up on the warranty, and the mileage on this battery pack is 98,000 miles.

I hope others who have had battery failure will speak up, so we can get some updated info on life expectancy.