Well, I mostly concur with BryndenBFish here. Roose has played his hand conservatively and smartly – turfing out the Ironborn from Moat Cailin to give himself Northern nationalist cred, building a base of supporters (albeit of uncertain loyalty), planting traitors in Stannis’ camp, and using the winter to his advantage.
My one critique would be that I think Roose has played a touch too conservatively. A small contingent of cavalry sent out to harass scouts and foragers, cut trees down across the pass, attack the supply wagons, etc. could have dramatically increased the pressure on Stannis’ force without risking much. As it is, Stannis was able to make the march largely intact albeit low on food, Something of a mistake there.
Also, I think Roose’s making something of an error in his response to the news that Stannis is less than 3 days away. Sending out the Freys and Manderlys has a number of political and logistical advantages, but it means that he looses the advantage of numbers on the battlefield – he’s sending ~2,300 men to fight ~5,400. Roose is probably hoping to whittle Stannis’ army down piece by piece while holding the core of his forces in reserve (and using the Karstarks as his psychological ace in the hole), but what he’s risking is that, if the Battle of Ice ends up as a (non-Pyrrhic) victory for Stannis, his core will be facing an army of equal size and superior morale.