Not much has changed. The campaign story starts off reasonably strong with the sensible motivation of finding your captured family, then the weird segue into the dragon banner section of the quest, then you meet Arzagos and Istiana in person and they have quite good dialogue and justification for their respective viewpoints, which is great for immersion.
After that, the quality drops off sharply, and the rest of the campaign is grindan quests, delivered through textboxes, with no character interaction and questionable logic behind them (why can't I just go kill Arzagos in Marunath when he's organising a conspiracy against me and I literally know where he lives?) followed by the experience of the last three kingdoms declaring on you simeltaneously and the resulting slow slow grind to take enough of their fiefs to force surrender, capped off by an extremely anticlimactic ending which is just a textbox saying "you win".
And doing the entire campaign in the first place is of dubious value too, because giving the Dragon Banner to a faction leader doesn't benefit you whatsoever, you make three kingdoms auto-declare on you at once, and you waste a lot of time doing the conspiracy quests.
The two good things about the campaign from a gameplay perspective is that it removes a little bit of grind from painting the whole map by making enemy kingdoms surrender when you take half their territory, and you get free family members as a reward for doing the Radagos quest.
Making the later stages of the campaign better - more benefit to the player for doing it, more drama and storytelling with characters, a more satisfying climax - would be great, but honestly while the current one is in a barely serviceable state and we have Sandbox, I'd prefer TW improves the sandbox first and tackles the main quest last.