Thanks Charles. The D7100 is a great piece of equipment, you won't regret the move. I had originally bought it just for wildlife but now use it for everything and my D300 has been relegated to the back up role.
Better images at higher ISOs. With the D300 I didn't like to use anything over ISO 400, although it was acceptable to around ISO 800. With the D7100, I've been up to ISO 1600 and had decent images and could probably go even higher.