We own a Toyota Prius and it's done ~111000 kms.
1) We did NOT buy it for that environment friendly image or to get great fuel economy. My parents are huge fans of new technology and so they simply couldn't resist owning something like this!
2) The 'fun to drive' factor is relative. Although the handling is not as sharp as a similarly priced German car, and nor is it as fast, it's still an experience to drive the Prius, and an experience I enjoy! When you hit the power button you're met with almost complete silence; shift the small joystick like gear knob to 'D' and ease of the brakes.... and the car moves in utter silence. Tap the accelerator and you can feel a mild whack as they electric motor thrusts all it's torque out. Up to speeds of about 50 km/h (given the battery has enough charge) only the electric motor spins. Pick up some more clip and the petrol engine kicks in. Seamlessly. There is absolutely no jerk or vibration and besides the sound (remember it's been quiet all this while!) there is no other real indication that the petrol motor has started spinning. Works brilliantly!
Say you're cruising along on the highway (only the petrol engine running), and you need to overtake that slow moving truck ahead - step on the accelerator and along with the petrol engine, the electric motor kicks in, giving you that extra 'boost' of power for a quick and painless overtake.
The battery does not charge with plug point like the Reva. It charges up when you:
- Let go of the accelerator; ie. when the car is coasting
- Drive downhill
- Brake
To be honest the steering feedback is, well, poor. It's a typical EPS unit that's extremely comfortable around town, but you don't get that *connected* feeling. Luckily however the steering weights up a bit when you pick up speed and you feel relatively stable at higher speeds. Also, the wide stance of the car makes it feel quite planted and crosswinds don't bother it.
The car feels brisk around town and closing those small gaps will never be a issue. 0-60 acceleration is good an you'll even surprise a few people at the lights

On the highway it does decently and is by no means a slouch. Keeps up well but it doesn't like being pushed further than about 135 km/h - wind and tire noise increase and the engine gets fairly audible.
3) The cabin has great ergonomics - everything falls in place and it's very easy to find a comfortable driving position. The rear seats are very comfortable and the legroom is great (really, the rear legroom is commendable!)! Feels airy and light. 4 people can travel very comfortably and 5 without much hassle. The boot is large and offers plenty of room for luggage (comparable to the Laura's boot). Materials are good - definitely steps up from Corolla/Innova but not as good as the Germans.
4) Fuel economy. On our typical driving cycle which is a split of 70% highway and 30% city we get ~21 kmpl. The car is never really driven keeping FE in mind and almost always has 4 passengers.
5) As you can probably guess we really love our Prius. Unfortunately it's become a trend to 'hate' on it online. Mostly by people who have never even driven it. Pity really! Great technology, comfortable, Toyota reliability, and FE all in one neat, modern package loaded with gizmos!
6) Buying the Prius in India is however, a whole different ball game. Being a CBU it's pricing is high. If you really love new technology and you're willing to try something different, it's a great buy - it won't leave you disappointed.