I played it a lot, and basically... I think I finished it - after 200-300 hours including cassandra / randy extreme.
The start is hard because, even if improved, the game is unfair. Cassandra always hits where it hurts the most so it's very, very predictable, to the point that later in the game she stops sending raids because they just get slaughtered. Randy doesn't care, but it's not much harder.
Thing is that the game is meant for a group of 6-8 active pawns and until you get to that critical mass, you can't do much. Once it's attained, you're basically invicible save for the "go to bed you've got flu / malaria / plague" event. So the "second" critical mass is 12 people. With that many, it's next to impossible to lose, whatever the difficulty level.
It's just a slow grind until you get whatever objectives you've set to yourself - and generally 2/3 of the game is still unresearched at this point. Main issue I have with this game is that reaching the critical mass where you're just waiting for the game to end is very, very early in the game. Most research are completely unneeded to make a stable colony. In addition, after a few hours you'd have a good idea on how to respond to events, and after a few games, you'll have a few patterns which allow 6 of your colonist to down an entire 50+ enemy raid, given appropriate weapons.
It's still a very enjoyable game while you're learning the mechanics, quite intuitive, and the modding community is very active. Some mod are very, very good addition to the game, like petfollow or hospitality. I can't really say, even if it's my main issue with it, that it has low replayability, because on one side, it has, and on the other side, I played multiple hundreds of hours of it.
PS: and melee isn't a thing. Ranged weapons >> melee weapons.