There are a few of us. I have the 2002 Prius. After 3 years and 35,000 miles I still love the car.
I've had no problems related to the traction battery. The basic design has been in production since 1997 (in japan) and battery failures are exceedingly rare. In California, the battery is considered part of the pollution control and so has a 10 year, 150,000 mile complete replacement warranty.
Do I think it's worth the extra money? Yes. In my case I was thinking about a much more expensive car (a Jaguar) so the Prius was cheaper by about $15,000. The other car we were looking at was a Volvo for $37,000. As you can see, the Prius at $23,000 (out the door) was not, in my case, more expensive.
If you are in the market for a car in the exact same class as the Prius, you may or may not find that you are paying a premium of several thousand dollars. By exact same class, you'd have to find another 4 door hatchback which seats 5 and has a continuously variable transmission.
Just kidding. There are no others with that exact configuration. You'd have to compare it to an automatic 4 door of similar size.
Ok, assume that you found a similar car, similarly equiped, and it was $3,000 less. If you drive it 12,000 miles a year for two years with gas at $3 per gallon and sell it. YOu re cost of ownership is really the purchase price +taxes - resale price + cost of gas.
In my case, my 3 year old Prius should sell for about $18,000 per kelly blue book. I've used about 770 gallons of gas at about 2.50 per gallon for a gas cost of 1925. Total cost of ownership if I wer to sell it today? $6925
Now take a similar car, the Totota Corolla. It's a bit smaller and the accelleration is not as good, but it makes a decent comparison. The 2002 S model sold for about 17,000 plus tax and lic, so right around 18520 out the door. The S model today will sell for 7,700 to 9,060 per edmunds.com
So the cost of that car is $9460 depreciation and at 34 mpg $2572 for gas. Total cost of ownership? $12032
Now if you are a person who drives his car till it's worth nothing and then sells it for scrap, the only differences are the gas savings, and possibly the enhanced reliability of the hybrid. The Prius engine is run more efficently and with less stress than a normal car. It does not idle at stop lights, for instance, so the actual engine run time is about 1/2 of a conventional car.
My comments have been directed towards the Prius, and not the others. There are vast differences in the design philosophy from the various car makers. The Honda Accord, for instance, uses the hybrid design to boost total power without losing MPG. The Honda Insight is a full blown fuel saver, but has a niche market due to the two seater design. Even so, the resale of the hybrid Honda's are still better than the gas models.
Even if you put the economics aside, the hybrids as a class do produce less polution than their conventional counterparts with similar performance. That's a plus no matter how you look at it.
Daniel