Well, I only paid $2 for this, and I feel that it is worth five stars for that price point.
The first section is a nice rules summary for navigating and getting lost, and even better than the rules were the commentary on when you should and should not push the exploratory parts of the game.
Similarly, the section on random encounters presents a nice system and again several very helpful comments on what you should and should not do with the system.
I think this file is probably well worth $3.00. More than that I would only give it 4 stars or so.