Dawn of War II is a sequel to Dawn of War by Relic and THQ..
Dawn of War II has a much slower pace in gameplay then the original and on a much smaller scale. Although this might come off to you at first as a negative thing but it tends to grow on you. Dawn of War II is also way more true to the actual board game and lore then the first one ever was and since it has those features it is very epic indeed.
There is some down sides to DoWII though, for example the only playable races are the Space Marines, Eldar, Tyranids, and the Orks. Compared to the last DoW Expansion Soul Storm which allowed you to play 8 different races. But it seems that Relic & THQ are going the same path with the original, adding a race per expansion i.e. Chaos Rising. Another negative is that the graphical requirements are much much higher then they were to play the original, so if you computer could play DoW perfectly you might want to check out the system requirements for DoW2 if you want the same FPS. Last but not least is the overall scale, DoW2 does not allow building of any buildings in the single player campaign or the multiplayer skirmishes. This felt like it limited DoW2's strategic possibility's but it makes up in the new cover system for it. The squad caps and over unit caps are much much smaller, some times it feels like the game should be called "Dawn of Battle" and not "Dawn of War" due to this.
Overall DoW2 offers an Epic single player campaign and multiplayer experience, beautiful graphics, true to lore and board game experience, and a unique new cover system not found in the first DoW.