I'll throw in my .02:
I see many many cars come through my shop with electronic parking brakes. Everything from Volvo's to VAG cars to Ford's to you name it. They all have one of two systems: an electric motor directly integrated to the caliper, which works exactly the same as the older ratcheting calipers, or an electric servo motor that engages brake cables, just like back in the day. Those are for parking brakes that use the "drum in hat" style rear brakes.
I've seen exactly one failure in my entire time working on these setup's, and that was on a coworkers A4. He went to go to lunch one afternoon and the RR caliper refused to unlock. Long story short, the EPB control module failed, sending voltage to the caliper motor constantly. This caused the motor in the caliper to lock up and smoke, because the module wouldn't stop sending voltage when the limit was reached. A used module was $450 and a caliper was ~$250.
Other than that, I've had no issues. Just make sure to follow the factory service information to the letter when replacing the pads, you can really screw stuff up if you don't.