The game of AI, or cognitive computing, is definitely afoot and IBM's Watson looks exactly like the sort of hero we want today. From a brand positioning perspective, what impresses me the most is the language, especially the visual language. The content strikes a great balance between text, images and video, with case studies and explainers doing the heavy lifting when it comes to persuasion. All very clean, but warm and with a very human scale to it. In this context claiming the word 'cognitive' seems quite reasonable and not as pretentious as it might be in a more techy environment.
What I deduce from my brief observation is that Watson's positioning works so well because it follows the maxim of keeping it short, simple and human. Or in this case, elementary.