As Fox are showing this from the beginning I am watching it with DD. We are two episodes in. A couple of things - the Zombies in series 1 are much faster than in the later series and are much more human and don't have the glazed over eyes of later zombies. They seem to look directly at the character and recognise people. Also they can manipulate door handles - the knobs on Morgon's front door is rattled in a very human like way. Rick has a completely different accent and Glenn is so skinny!