Coming from both Dwarf Fortress and Prison Architect, two games this one takes a lot of inspiration from, I had little problems with adapting to the game. However I see the flaws in the (current) game design.
The biggest one are the frenzies on wild animals. They happen without warning (you get a message that they happen but at that point it's too late), they are way too overpowered for somethign that can happen in the earliest game days and they destroy your entire preparations just because the game RNG decided to hug you. I know where the idea comes from but the current organization of it is bad designed. Dwarf Fortress had random events where anytime any lving being could go berserk and start attacking anything nearby (mostly your dwarves). For your dwarves it was called "throwing a tantrum" or something like that but the thing is, you could prevent it if your dwarves get what they want. I don't know the rule for animals but it happens way less to them and as far as I know they will only do this if provoked.
In Rimworld however it happens if you do nothing and the animal, even if its a tiny squirrel, will tear its way to your colonists and kill everyone on sight. And the tiny squirrel is for some sick reason unbeatable because this is the second biggest issue in the game: The combat system is crap.
The combat system works never out for your colonists. Never. the only way to be sure that they will survive battle is to build a lot of obstacles and turrets int he way. because you can be sure, they will die if they try to hunt any animal or at least get hurt and THEN die because of a minor scratch. Melee weapons are in my opinion the only viable option at the moment because the aim of your colonists is worse than from an emperial storm trooper. But the risk of getting scratches that kill your colonists is also very high during melee combat. See what they did there? You cannot go into ranged combat because your colonists will NEVER EVER hit. I tried this multiple times and the only time they hit was when they accidentely shot the dog pet you have on the start. And then the dog died after four days of misery.
Melee is also no option because even if your colonists can hit there, they get also hit and get minor injuries. But the way the game works is that even a minor scratch will always develop into an infection that kills you. Always, no exception. You may still live through some days but it will be in pain (the game has even a pain indication just for that).
The medical system is also crap. Like mentioned above you will always die, even fromt he tiniest damage. That's because the game does not differ between damage amunts. well it does, it clearly says if it has a minor scratch or a serius injury but the problem is, that's basically a timer to death. the more serious your injury is, the faster you die. But the problem is, you die anyway, just slower if its a scratch. You can treat injuries but most of the time you have to force them do it (and even then they kind of reject it) because the doctor labour does not seem to work correctly at this point. You can have docotors but they will neglet patients. Instead they will do other stuff. Unimportant stuff. And any untreated injury will develop an infection which kills you 10 of 10 cases.
The game tries in my opinion too hard to to be a hardcore experience, similiar to Dwarf Fortress. But it fails there because it is more like "I wanna be the guy". It throws unfair situations at you and depending on your luck you will survive them or not.
