Medium mode is a fun challenge at first, eventually becoming fairly chill as you advance in skill and confidence.
Hard mode is always fairly hard, especially on harder maps.
There are many resources to manage, but none that feel burdensome.
The game is extremely thematic, it feels alive with charm.
Graphics are excellent, though sometimes graphical glitches can still be encountered.
The water. It's so hard to explain to someone who hasn't encountered this system before, but water is life in this game, and it's both beautiful graphically, and extremely well simulated by physics. Learning to control the water, and see the shortest paths to end water scarcity with beaver engineering is an amazingly fun and unique aspect of the game.
Mods are well supported and the community is vibrant.
Cons:
Not a ton of content. They've been very good about adding new mechanics (badwater, extract, etc) but there's still just 2 races of beaver and a dozen or so maps.
No directed experience. In similar games I've enjoyed a campaign, challenge maps/scenarios, weekly challenges, a deeper progression system, just... Something to optionally set your goals. There's nothing of the sort in the vanilla game. It's fully open ended and there's only one unlock outside of your progress though the resource tree in a map.
All in all, I highly recommend it, especially at the modest asking price. If you love city builders, charming and beautiful art, thematic settings, dynamic challenge, and solution engineering, this is a fantastic game for you.
Other games I've enjoyed that scratch similar itches:
KSP
Cities: Skylines (but Timberborn has been far more compelling)
Factorio
Mindustry
Planet Zoo (Timberborn has less of a directed experience, but is otherwise completely superior)
Gnomoria
Banished
Tropico series (though I view this as more casual)