He looks really great, but that's definitely not a member of the Deathwatch. Armor isn't painted black. That isn't the Deathwatch insignia on his shoulder. Close to it, but not quite. But even if it was a spot-on Deathwatch insignia it would be wrong, because Deathwatch marines are given special silver pauldrons that they wear on the left shoulder. And Deathwatch Marines keep their original Chapter insignia on their right shoulder, and it looks like his right shoulder is blank.
Don't get me wrong, he's a great looking Marine! Just not a member of the Deathwatch.