So far my Cobalt has been great. I have the LS Coupe (5spd) with sport package. I have not had any problems at all. Gas mileage is ok; I get about 30-31hgwy, 23-24 City. Performance is pretty good; more standard power then civic or corolla. Ride is comfortable; very quiet also takes rough roads well. If your a fan of driving stick, like me, you'll enjoy how this car shifts. Its smooth and not boxy like other cars. I'm very happy thus far, other just missing the emlpoyee discount.
Definitely the radio. I have the 7 speaker pioneer system with 10 inch sub. Sounds Great! Also the driver info center looks good.
One thing I don't like is the plastic in the interior. I have noticed that the plastic on my driver armrest is scratched up from the buttons on my jacket.