I think, and I hope, that the team that made Shogun 2 is on this. The recent total wars have many problems, but to summarize all I can say is this.

A complete and total failure at the synergy between Music, Gameplay, Visuals, Strategy. Exactly what Vardeus said.

Shogun 2 had this to such an extreme level, that it hit you at an emotional level sometimes. You got an attatchment to your agents, your generals, and felt glee when you finally took Kyoto whether you assaulted the walls with 2 full stacks and artillery, like me, or you lured out the Shogunate and assinated then isolated his forces, etc. At the base level, it felt like Total War in fuedal Japan and could stand on it's on.

Rome 2 totally and utterly failed at this. Music was based, was totally disconnected from the gameplay which was a complete downgrade from Shogun 2 because of how buggy and ugly it was. The animations were a mess, the battles were fast and the AI was bad. The campaign had more scale, yes, but felt incredibly shallow and turns took alot of time for such simplistic gameplay. The province and army systems only dumbed the game down, by removing control of garrisons and adding stupid factors like Carthage somehow making Nova Carthago Gallic while Carthage is owned by Rome and Nova owned by Gaul. It doesn't make sense. Not only that, there's a total disconect between factions and gameplay too. Rome just has alot of sword infantry, parthia just has useless infantry and heavy cavalry, greeks just have ugly hoplites, etc.

Attila did slightly better, but the music is still rather bland, repetitive, and unexciting and is disconnected from gameplay. Strategy in the gameplay is much better, however it feels very frustrating if you don't have cavalry heavy armies since Impact is such an overpowered stat, hit something with shock cavalry or even melee cavalry and you will likely route a unit unless it's in a shield wall. You can even route higher tier spear units if they are moving or not in a shieldwall. Game is ugly in my opinion, shadow draw distance is so awful environments look bad, especially if you turn of absurdly performance hogging AA. But the ugliest part is burned material and the brown asthetic, occasionally the game can be very colorful but for the most part it is just low def, similar looking armies and units in a brown environment.

Warhammer can do better, and I hope it does. The cinematic trailer music sounds great, if they can make the gameplay like it or atleast write music to match the gameplay, then the game will be far off better. Not only that, the art style and visuals need to be colorful and fantasy, Total War has never handled gritty realisim that well. Shogun 2 was a colorful japanese painting, I'd say fantasy-lite but people will argue against that. It is by far the most beautiful total war game yet, you can see it everywhere. The samurai look great, the animations look great, cavalry charges look great, forts and environments look great (some environments have vista's that are just jaw dropping), the lighting and overall color of the game is friendly to the eye and have aged well. Hell I'd argue particle effects look better than Rome 2 and Attila, I could literally prove it with screenshots if I have to. The detail in Shogun 2 was and is incredible, if this could be done with Warhammer then the game will succeed.

TL;DR I am going to make a thread about this post, and I totally agree with Vardeus.