Drive by wire works fine, its reliable. The biggest problem I've seen GM customers have is that they don't take care of their cars and see what the check engine light is on for. The throttle body and throttle pedal each have 2 sensors in them, so when one fucks up you can still drive the car, however some dumbasses let it go until the other one goes out and the car doesn't move. I find this pretty funny and I've seen it a few times.
Personally I'd rather have the control over the throttle body with a cable, there are lots of reasons the computer would close the blade and you have no control. Even when you tune it, it doesn't make it act like a cable. I don't like it in performance applications. It isn't as easy to modulate the throttle, and no matter what anybody says its still slower, some worse then others. DBW wouldn't be a deal breaker for me, but I don't really care for it.