Big change this year is with the skating physics; players now skate with realistic weight and inertia.
They also moved more towards realistic skillsets of the avg hockey player - bigger players cannot deke and maneuver as well as smaller players - and smaller players have more difficulty delivering big body checks, for example. Also, only the best players are able to execute skill moves and accurate shots while moving at top speed.
You very much have to tailor your player's size and skills to your playing style in NHL 13.
So, yes, there's a big jump from 11. My only complaint about 13 is their decision to not use vision control - which makes it tougher to square your player up to where the puck is.