The downfall of these cars is the time it will take you to recoup your investment over a non Hybrid in a small high mileage car. Depending on driving habits and mileage it could take 10+ years before you recoup the $5000.00 of additional investment from fuel economy savings.
This is often the problem introducing new technologies; it's initiallyy very expensive, but when it works out, scale fixes things. Cellphones are a good example. There's an absolutely incredible amount of computer and software technology in even the crappiest modern cellphone, and they're now available for nothing in thrift stores (usable GSM phones).
Individuals buy for component cost (whatsa car cost me?) but the overall system cost (car, fuel, fuel supply, pollution, health, road maint from drips, recycling) matters too, or ought to. With air pollution increasing in places, and gas costing $3 and up seeming without limit, etc, the scales seem to be tipping that way.
It's too bad for me they all seem so soulless to drive. I dislike even plastic interior parts; my 1970 Hornet was a hard compromise for me to make, but at least I was able to make it my own colors, and not Corporate World Market Neutral Gray.