Get. This. Game.
It got GOTY for a reason.
Having played Warhammer quite a bit in after-school clubs and such, I was somewhat skeptical. The only other Warhammer game that I had played was Chaos Gate, and, needless to say, it lacked quite a bit. Dawn of War, however, is completely different.
This game just blew me away. Even though the tutorial became somewhat annoying after the first fifty little snippets of voice, you only need to play it for about five minutes before you can jump into a mission, with the basics of the game, and win with relative ease. But that's only mission one.
Everyone is true to their own race. Space Marines are a blind boltgun, Chaos is absolutely off it's head with power and corruption, the Imperial Guard have crap Morale but big numbers (Hell, they have a penal legion. The Raven's probably got /that/ regiment.), and the Eldar are all knowing.
On the whole, this is a really well put together game. Even though I am slightly disappointed ot not see all the units available (Bike Squadrons, Terminator Seargant and such), it was a pleasant surprise to see a tabletop game turned into such a polished piece of entertainment.
I look forward to buying the expansion packs, and if you don't have this game, I'll say it again. Get it. You won't be disappointed.