Approximate time to finish the main game: 1.5 hours
The Beginner's Guide shares a lot of similarities with The Stanley Parable, which makes sense since the former was created by one of the minds behind the latter. Both are clever, unique experiences that have something to say.
With that being said, they're also complete opposites in many ways. The most notable difference comes in their focus. The Beginner's Guide isn't so much about the player but the creator, and you realise that the whole thing is a deeply introspective piece of work for Davey Wreden, who not only made the game, but narrates it. That's also the biggest link between the two games, because one seems to be about the experience of creating the other. That probably doesn't make sense, but it might if you've played them both.
The game hits suprisingly hard, and left me with a heavy weight in my chest; I was still thinking about it for some time after the credits had rolled. Any game that can have that effect is surely worth playing through?
If the game piques your interest I would definitely recommend playing The Stanley Parable first, if you haven't already. I found that as a consequence of playing that game, it affected my decisions in The Beginners Guide; I was always looking for ways to defy the narrator. I'm not sure if this was coincidental or something intended on Wreden's part, but I'm prepared to give him the benefit of the doubt.