There actually a lot of CG used in movies which people don't notice. Generally, if they are actually trying to fool you it works surprisingly well. Consider, movies don't show vary realistic explosions not because we can't do it but because stylized balls of fire look more interesting than flashes that end in a single frame. It might be hard to do realistic humans but, watch this: http://www.youtube.com/watch?v=iWE18YjLA8U it starts do really unnatural things and yet it does not scream CGI.