Like other folks said, though, sometimes ABS seems to kick in for no reason at all. I've had this happen to me a number of times backing down one of my friend's driveways, which is fairly steep (30% grade or so), and not being able to stop is scary, even when it's a quiet neighborhood. This is on totally dry concrete.

The problem is not so much that the technique is invalid, but the implementations can occasionally leave something to be desired.