That's one of my favourite comments ingame. Many people see the war as Imperials vs. Nords, failing to realise that it's a civil war and that many Nords, such as Hadvar and his uncle, the battleborns, etc, do in fact support the Empire and think poorly of Ulfric or the Stormcloaks.
Personally, I roleplay an Imperial and think that the Empire is largely beneficial for Tamriel and that Ulfric is not. For the sake of brevity, I won't outline the entire argument here, because I've already done so in countless other threads from since long before Skyrim's release, and because this quintessential 'legion or stormcloak' topic pops up again and again.
Suffice to say that I believe Ulfric's motives are suspect and that his actions will have extremely negative repurcussions that will impact beyond the borders of Skyrim due to Tamriel's current state of geopolitical tension, and that people undervalue what the Empire stands for and has achieved in Tamriel, loving to jump on the romanticism of 'braveheart' freedom fighting without understanding what is at stake.
Oh, and I'll drop this copy/pase of a previous post of mine from a thread of things you hate:
Spoiler Things I hate:
The Thalmor. They sacked Anvil, Skingrad, Chorrol, Bravil, Leyawin, and Cheydinhal. They sacked the Imperial City. They butchered entire Legions and put Cyrodiil to the flame, and might do so again. As a proud Imperial, I loathe them for that with incredible passion. I detest them and resent their existence.
The second group I hate are the Stormcloaks. I hate that they think of themselves as victims against Imperial and Thalmor cooperation when they forget or ignore what Cyrodiil suffered in the Great War. I hate them for their misguided stupidity. Most are fool peasants with dreams of grandeur and romantic uprising, merely ignorant farmers being misled into civil war by a powerhungry usurper willing to risk the geopolitical stability of Tamriel itself to advance his personal ambitions. Ulfric would betray the benevolent Empire and hand its corpse to an intolerant and zealous (much like himself) Alinor on a silver platter. No suprise, perhaps, given his shady past.