(1) The Chevy Volt ultimately runs on gasoline (the backup after the batteries die) and coal or nuclear power (to recharge the batteries).
(2) Creates a huge toxic waste problem where none existed previously. The exotic battery packs are Hazardous Material and require proper handling during servicing, refurbishment, or disposal (including recycling or salvage).
(3) Will require replacement with a new or refurbished battery pack, costing thousands of dollars, after five years (or sooner). This is the equivalent, in a gasoline engine car, of replacing your engine with a new or rebuilt one after five years! (We all do that with our conventionally powered cars now, don't we?)