I'm on the fence. I hate "machine gunners," be they digital or not but I also like the idea of being able to concentrate on making the picture and not whether I advanced the film and cocked the shutter.
Motor drives can be valuable tools to capture fast action, the finish of a horse race, for instance. However, even in that circumstance a three-shot burst is usually all that is called for. One problem is that, even with a motor drive, you often miss the moment you were shooting for. You'll get the split-second before the horse crosses the finish line and the split second after the horse crosses the finish line but not that "golden" moment. You might just be better off shooting one frame and trying to time the shot for the right moment.
Much as I like my motor drive, I still call it "The Electric Film Burner."