Dependability. Periodic ordinary maintenance, that's it. Brakes lasted well over 100,000 on my '02, so did the plugs. Quiet, smooth, and I am getting 55 mpg with my '11 Prius. Exceptional rear seat legroom and overall comfort. My '02 will still be on the road, except it was clobbered and totalled. I had 164k on it, and no question it would have made 250k. ore more. Only needed a waterpump after 150k. Amazing performance by A/C even after 15 years on the road, didn't burn a drop of oil, engine was very peppy for a 1.4 liter, and 50+ MPG was easy to attain. Drove cross country 4 times with no issues whatsoever, and it cruised smoothly at 70-80 MPH. At those speeds, mpg was 40-45, which I still considered outstanding. We have a '13 also.
I'm big, 6' 2". The car has plenty of head and leg room. I commute 95 miles per day and the Prius handles well, winter, summer; rain, snow, sleet, and dry. It is light and nimble. Using the power button the car's transmission allows the car to accelerate with the engine RPM's held in the highest torque band of the engine. It is surprisingly quick. Turn off the power button and the car get mind blowing mileage; I am averaging between 50 and 55 mpg on my commutes. The heat and AC are excellent. The headlights are absolutely outstanding.
I owned a 2006 Prius for 10 years before purchasing my 2015 Prius Three. My 2006 had 49,500 miles on it when I traded it in and was an excellent car to own. So far my new 2015 Prius Three has met all my expectations and I am very pleased with my purchase.