I've only played 2 scenarios so far, but they were pretty engaging. I must say, I was surprised at the difficulty level, which seemed to be fairly easy. The very first play-through I made terrible decisions all along, but still somehow beat the game despite running out of food, heating and 1/2 of my population. I would have preferred the game to be a bit more punishing for bad decisions, perhaps I should try a harder difficulty. Overall this goes on sale for $20 and below and I think it's worth every penny. Great art, cool tech tree, interesting decision making all make for a solid game.
I found Firewatch to be funny, intense and engaging. I wasn't really looking for replay value - so I don't consider that in this review. It's a very beautiful game that's a joy to walk around in and the story it tells is very interesting and intriguing. I would agree with other reviewers, that perhaps the game choices don't really lead to different paths, but I really don't mind since I just wanted to play the story along and enjoy the experience. Is it $5-$15 worth of fun? You betcha, compared to the latest Star Wars - I would have much rather replayed Firewatch once more, but we all make bad life decisions, so hopefully you'll make a better one.