I've had this car for over a year and it's been a solid performer. I've only had one issue (warped rotors) and they were replaced under warranty. I get great gas mileage, especially on the highway. The car is a blast to drive and really gets up and goes. You'll have a hard time finding a car with as much torque and power as this one has for the price (and for being a naturally aspirated 4 cylinder).
This car sold me on the styling and the motor. The car looks great in my opinion. But more importantly, this is a solid motor and drivetrain. It really performs. The motor is advanced for the market and when tweaked with aftermarket parts, really responds even more.
The only complaint I could ever have is the interior. GM, Chevrolet especially, is known for lesser quality when it comes to interior. While this interior is better than the J-Body line that the Cobalt replaces, it could have been refined a little more.