For those of you who have begun playing it. Are there actually new creature
models in the game or did they just take existing models and change the colors?

there *are* new models, but these are "borrowed" from Icewind Dale.

it is extremely difficult to make completely new animations, and these then have to "override" ones that are already in the game, so it is very difficult to do effectively.

but there are definately new ones in there!