If you are looking to buy a Prius, my guess is it's because of the gas mileage. If so, the money you save in gas, use to buy an insurance policy, especially if you live anywhere you might get snow, ice or rain on the road.
Once the wheels start slipping, the engine shuts off and the car losses momentum and will stop, DEAD. Dead in, not able to move, possibly on a hill, possibly with traffic coming at highway speeds and you can't even get to the shoulder of the road. But this only happened to me whenever it snowed.
When this happened to me, I almost got rear-ended by a tractor trailer making speed to get up the hill. If this wasn't a loaner car, while my truck was being repaired, I'd have left that car in a ditch and hitched to work everyday.
This is a dangerous situation with this car and you need to be aware of it BEFORE you buy one. What may be deemed a safety feature by some at Toyota equates to a life threatening situation to others.