I haven't read MANIAC (yet) but a few years back I was trying to find a good biography of Von Neumann and there are not many; the problem is that he's really difficult to cover comprehensively, even for science historians, because he impacted so many areas of science that you'd practically have to be a von Neumann to create a biography of von Neumann. One could probably get a rough idea of his intelligence by how many science historians it would take to create a comprehensive biography which explains his life and work to a reasonably intelligent layman.