The game's fun enough for a while, with mods, but the fun wears off quickly. The economy is never really explained, and from what I've read, it's much shallower than it appears. So many of the mechanics, from generals to battles and rebellions and political parties, feel half-finished and get more and more annoying as time goes on. The AI is dumb, very dumb, but the cheat bonuses it gets are obscene, so unless you snowball, you'll always be on the backfoot. Very little flavor, very little variety in diplomacy, and very little variety in playing each country, it just gets so old.
This gets compared to The Last of Us all the time, but I'd honestly say it's a better game with a better story and mostly likable characters. It's rough in a lot of areas though. The story, while unique in some ways, is standard and predictable in others, and feels simultaneously padded and missing content. Sadly, a lot of content was cut before release, including a major decisions system. The combat is enjoyable at first, but eventually becomes repetitive and far too easy, even on Survival II - the highest difficulty. Both human and freaker (zombie) enemies have only two fighting styles: sitting in one spot and inaccurately shooting at you, or charging straight at you. No tactics, no situational awareness, and no reactivity to the player, things that The Last of Us did surprisingly well. Nothing deep on the player's side either, boiling down to mashing buttons in melee or spamming a slow-mo "Focus" mode in ranged. The higlight of the game, its hordes, are fun and challenging, but they're static setpieces that never form naturally and only a couple of them ever respawn. Since you run into the biggest one in the game early on, you pretty much see them all. The game does look gorgeous, and playing on Steam, I never noticed any performance problems or stuttering. It sounds good for the most part, but some voice lines are inconsistently recorded or delivered (Deacon shouting at the top of his lungs during stealth sequences became a community meme) and the faces of minor NPCs look noticeably worse than the main characters. The soundtrack's great, with a subtle, "zombie western" style - think Telltale's Walking Dead games. On a scale of 1-10, I'd give this somewhere between a 6 and 7. It's a good game, however, that got unfairly maligned by critics at launch. Regardless, it needed more time, more story content, and a combat overhaul. On sale? More than worth it. Full price? I'd give it a pass.
The first act is great. It's like a sidescrolling zombie survival with tough combat and interesting puzzles, and it feels good to play. Then the second act completely falls apart. The story and setting become a nonsense fever dream, combat is replaced by increasingly ridiculous puzzles and nothing but, and the tedium and frustration skyrocket. I didn't finish the third act because the second was just so awful to the point it felt like the first act had been made by different people. Great at first, goes to hell fast.