I hear you. Perhaps not an overview then, but an example of a solved or unsolved problem?
While Google's virtual brain "understood" something, it still doesn't has the ability of analysing. This is an example of unsolved problems.
Eg, you ask the virtual brain 'why is the sky blue?' 'why is the sky sometimes grey?', and it may not tell you why.
Google's virtual brain can 'recognize' things from the images, but it cannot handle the logic problems or something like that.