Although Kasparov won his first match against IBM's Chess-playing computer Deep Blue, he lost the rematch, and didn't handle the loss very well. Obviously, he's thought quite a lot about the man-versus-machine contest in the ensuing years, and he offers some interesting comments about Watson in The Atlantic:
My concern about its utility, and I read they would like it to answer medical questions, is that Watson's performance reminded me of chess computers. They play fantastically well in maybe 90% of positions, but there is a selection of positions they do not understand at all. Worse, by definition they do not understand what they do not understand and so cannot avoid them. A strong human Jeopardy! player, or a human doctor, may get the answer wrong, but he is unlikely to make a huge blunder or category error—at least not without being aware of his own doubts. We are also good at judging our own level of certainty. A computer can simulate this by an artificial confidence measurement, but I would not like to be the patient who discovers the medical equivalent of answering "Toronto" in the "US Cities" category, as Watson did.Read the whole thing.
h/t: My wife (again).