Last time we checked in with Aurelia, the Space Marines were fighting the forces of Chaos (in the first Dawn of War II expansion, Chaos Rising), and in the process sort of saving the day - or not.
Six-playable races; Introduction of some more RTS-y elements; Expanded multiplayer
More of a side-step than pushing the series forward; Campaign story a lot less focused; Possibly even gibberish to non 40K fans