According to lead game designer Christina Norman, "If you love intense shooter combat and carrying way too many guns, when you play Mass Effect 2, you'll want to play the soldier."
Mass Effect 2 is setting its sights on the Modern Warfare 2 crowd, and the soldier is a class aimed right at that demographic. The soldier doesn't screw around with magical powers. The soldier is all about guns and the shooting of ammunition from said guns, generally in the direction of the bad guys, though your results may vary.