Santana Row works as a walking area rather than a single attraction. Its value is in the streetscape: the small changes in architecture, shops, squares, riverfronts, or public spaces that show a different side of San Jose. It is a little away from the tight centre, but still close enough to fold into a half-day plan if the subject interests you.
Do not rush it. Pick a sensible starting point, wander with a rough route in mind, and leave time for a cafe, viewpoint, or small museum if one catches your eye. Neighbourhood POIs are often most rewarding when they are allowed to be loose.