I think overall, it meets its design specs. Roughly 33 miles on a charge. It really does depend on how they drove it. 33 mpg is OK, not great but OK. I would say it comes down to the initial cost and operating cost. I don't its size, but I would gues a compact car. So probably compare it to a Ford Fiesta, Toyota Corolla, Matrix etc. They get 41 mpg highway, maybe a bit better. I think that class of car sells for $12K to $16K. So, $15K for gas, then the interst on that over 5 years. I calculate roughly $1200 in gas per year, based on 15K miles.
So, I think it is a bit of a novelty at the moment. Al technology starts at a high $ value. ABS, airbags, computers etc. Scale of economy, improved production techniques etc. should bring the cost down. So time will tell. I like the approach they took with the Volt.
Tom