I don't see what exactly you could love about it. There are no difficult choices to make, no particularly interesting situations and lots of room for frustration.
There are many difficult choices to make, one common one is fighting or avoiding enemy LLs in many of the realms. Every layer of Slaneesh is a difficult choice. In general the way campaign works is full of difficult choices because of the competition and race to souls. You never really feel comfortable or safe. It feels like playing an Attila Total War campaign which I also loved. Trying to persist rather than "blob & chill".
My only complaint about any of them would be that I think there are way too many armies in Tzeentch realm. Aside from that I enjoy all of them, I enjoyed Tzeentch too the RNG and mapping of it.
Is that a joke? There's zero 'choice' in any of the realms. Unless you're terrible at the game, none of the AI are going to beat you to any of the realm goals unless they accidentally luck into it in the RNG Tzeentch realm before you can ID the path. There's zero reason to fight them unless you want their LL traits. All of the Chaos realms are incredibly straightforward, with the exception of the Tzeentch portal RNG. Nurgle you walk to the point and then walk to the quest goal, that's it. Khorne you fight a couple respawning armies to get your points and then walk to the quest point. Tzeentch is annoying RNG, totally dependent upon you picking lucky in first portal, and then IDing enough to make informed choices from 2nd island, and paradoxically is the domain that may require the most fights to beat because there's several forced fights moving around the little islands and you have to fight them to mitigate the RNG. Slaneesh is a joke, you don't even have to do anything other than walk in a straight line between portals and you don't even have to fight. There's one or two bribes that have reasonable benefits, but there's no reason to take them unless it's the absolute first portal you entered - why would I need money and a few levels 60 turns into the game? And most of the other realms give large amounts of money and XP from all their fights anyway. Sure, it's a legitimate strategy to rush into Slaanesh first and take one of the big bribes, but honestly the only reason to do that is if you aren't actually capable of winning the quest fight, since if you DO take a bribe, that prevents you from actually getting a soul that round, you just added 30 turns to the length of your campaign for an extra round of portal spawns.
And the quest battles are a joke, they're all exactly the freaking same with only minor and unnoticeable differences with the map gimmicks. They all just follow the same pattern of move forward and kill laughably small army on point, cap point, build a couple towers, sit and wait for spawnwaves, move to next point, build towers, wait for spawnwaves, move to final point, build towers, kill laughably weak Daemon with a ton of HP, mop up final spawn, win. It's so dumb - why are ALL FOUR of them battles just cosmetically different? Sure, Khorne's thing should be just throwing waves at you, but why is Tzeentch doing that instead of throwing spells, illusions, and elaborate plans at you?
As far as the main map goes, it's a boring drag. There is ZERO incentive to expand on the normal campaign map further than is necessary to sustain your LL army and a single lord back home. In fact, expanding past just a small handful of provinces means that you are forced to park lords all across your territory to deal with the portals when they spawn, and since there is NO BENEFIT to the actual victory conditions to have more territory, all that does is waste time. The campaign very much encourages you to simply turtle in a corner and mash the end turn button continuously.
I wasn't the biggest fan of Vortex but at least it forced you to expand to the point you could beat the large later invasions, and you HAD to control a certain amount of territory to finish it in any kind of reasonable amount of time.
This is a pretty poorly thought out mechanic, where the ONLY thing influencing the portal spawns is the turn timer. After the first portal or two you're invincible and just mashing the end turn button waiting for the next spawn cycle. and since the game gives you multiple turn warning, there's no reason your LL shouldn't be fully healed and ready to enter portal within 1-2 turns at most.
The campaign is definitely the weakest feature of the game because there IS no meaningful choice.
If you were going to shoehorn us into this, then they should have put in the time to make it a scripted campaign like the Prologue, that was 10x better than the full campaign.