Fun, fast paced combat.
With a strong voice acting cast, and great drama, this singleplayer campain really felt alive, the characters defined themselves and when something happened you cared.
It was challanging but not impossible on hard mode, I even managed the achivement for part 1 in a single session and no deaths.
Multi-Player is fun, fast, and filled with blood pumping fury as you slash, stab, chop, smash, shoot, blast, blow up, and otherwise destroy your enemys.
I believe that more then any other shooter I have played this requires skill, cunning, and quick reflexes to play well, and as some one who was called, "The Soul Drinker" by the Onlive mult-player community before it died, I can attest to the skill required.
Saddly The online play is a little empty some times, but it's still possible to get a game rolling, best to have friends that play.
All in all a good buy, the 50% off the Space Marines Pack on steam is a good choice for now, it lasts until January 05 2013.
Have fun and hope to see you on the battlefield.