I wouldn't say bad, but certainly not as efficient as disc brakes. For many years drum brakes were the norm. I have many classic cars which have drums front and rear and they stop just fine. Ironically the MGB in my avatar was ahead of it's time in the 60's by using disc brakes. I regularly drive a 4x4 with drums on the back. Weighing in at two tons it takes a while to bring it to a halt. I'm just aware of the stopping distance required and adjust my driving style accordingly. A lot of economy cars do in fact use drums in the back to reduce the cost. Most of the braking is done from the front of the vehicle and this is standard safe practice. It has been the norm for years. Having said that I wouldn't buy a new car unless it had 4 disc and ABS, but then again I wouldn't buy an economy car. ;)

Drum brakes were phased out in most cars long ago. The calipers can't exert as much force on the rotating drum as what can be acheived with disc brakes, and they are a lot heavier. Still, I don't mind Focuses (Focuses or Foci?) from what I've read, although I haven't driven one.

The two sides of a rotor imply twice as good at least. And better cooling.

no they aren't bad. the rear brakes only supply a small percentage of your braking power. they slammed them because they are a generation behind.