TLDR really cool concept, execution is a bit sketchy in places but this review was only written a few weeks after release so hopefully there will be some rebalancing and other QoL updates that fix some of the problems below. If you like management style games you'll probably enjoy this, a lot of the systems feel quite similar to Darkest Dungeon as well so if you liked that game then definitely give this a go. I've finished the story, but there's some completionist stuff remaining that I may get round to finishing at some point.

I have a lot to say about this game so this is going to be a long review. Some of my gripes might be fixed with updates, so this is as much feedback as it is a review.

Really good design decisions
The basic idea behind the game has been covered by loads of reviews already, you go on expeditions, in which your hero automatically walks round a loop fighting enemies, and when they defeat enemies you gain cards which can played to place tiles in the world, equipment which buffs your hero during the expedition, and resources which you can spend on permanent upgrades and new card unlocks in-between runs. Prior to each expedition, you can equip 'supply items' to give yourself a boost, and construct a deck of cards which determines which tiles you will be able to place during the run. The different tiles spawn particular types of enemy, and provide buffs to the hero either when they are adjacent, or globally. Certain tiles will transform when placed next to specific other tiles (for instance, a Meadow tile transforms into a Blooming Meadow when placed adjacent to any tile that isn't a Meadow or Blooming Meadow), and part of the fun of the game is discovering these interactions by yourself. The meat of the game comes down to setting up a world in which your hero is given the specific buffs they need to farm specific enemies as quickly and safely as possible, because once sufficient tiles have been played a boss will spawn, who will destroy your hero if they aren't levelled up enough. Concocting builds is a really interesting puzzle, and unlocking camp upgrades with different resources incentivises you to avoid using the same build every run. There are 3 distinct hero classes, and around 25 different cards to play with, so you have plenty to think about. Camp upgrades are required to unlock 2 of the 3 classes, most of the tiles, and many additional mechanics, so the full complexity of the game is not thrown at you immediately. The various tiles all do interesting things, although some of them are really not useful in practice (more on this later) and the balancing act of making sure the difficulty of the loop doesn't go beyond the hero's ability to fight it is really unique. The art style is very cool, and while the worldbuilding and lore isn't fantastic, it could definitely be worse.

Less good design decisions
I have quite a lot of gripes about the game, so I'll address each one in turn. The first one to get out of the way is the limited options for speeding the game up and avoiding having to watch fights. I won't say much about this because it is apparently due to be fixed, but for now bear in mind that there is some wasted time.
The game doesn't expect you to beat the boss on each run, it instead expects you to retreat when you're not strong enough and use your resources on camp upgrades. The problem is, if you don't retreat immediately before the start of a new loop, you lose a portion of your resources if you retreat anywhere else, and you lose even more if you die. Given that there is substantial random variation in the effective strength of a given loop due to random unit targeting and semi-random enemy spawns, this asks you to correctly make a very complicated estimation about whether you will make it around one more loop, which makes it very slow to initially get going with camp upgrades before you know what you're doing.
The game hides far too much information. There is an unlockable 'Encyclopedia' which records information about enemies and tiles you've seen, but it is missing huge amounts of information, such as enemy stats and loot value, which turns the game into either lengthy trial and error or tedious recording of things with pencil and paper. At one stage I discovered a hidden tile that grants extra "magic damage", but given that the game tells you nothing about how "magic damage" works, what enemies it's effective against, or anything like that, I just never used that tile. I feel like there is probably a lot of extra depth to the game that I am just missing out on, because the game never reveals it to you.
Finally, the balance is pretty poor, and this also hurts the variety in ways to play the game. The Rogue is by far the best class, with so many broken interactions (Arsenal, spiders for mass trophies, outposts, forest+desert+crit stacking) that they leave the other 2 classes in the dust. Similarly, many of the tiles seem so bad that there's no reason ever to take them unless you haven't unlocked anything else [spoiler](mountains, swamps, storm temples, treasuries, chrono crystals)[/spoiler]. It's hard to tell whether there are in fact hidden uses of these tiles that actually give them a situation in which they are good, because the game doesn't give you enough information to ever justify picking them, and my experimentation hasn't been particularly successful either, so I can only assume they are just bad. Hopefully there will be major rebalances and clarifications to the exact effects of all the tiles, because the game system is really promising and open to expansion, so hopefully there will be more content added in future.

Final thoughts
For a lot of the time I spent playing this game, I kept coming back to the thought of "Wow this is a cool idea, hopefully someone else will come along and make a better game based around it". My attitude has softened somewhat as I've got used to how the game works, and there's no denying the core design is really clever, but it does still feel pretty rough around the edges. Hopefully the devs will fix a lot of the more glaring issues that have been pointed out since launch, and in any case I'm interested to see what happens with this game down the line. Definitely deserves most of the buzz it's been getting.