[scott_s]

Don't look at it as a threat, because I don't think the user intended it as one. He's not saying "Fix this bug or else I will stop playing." He's saying "Not fixing this bug will cause me to stop playing."

As for the rating, he's saying that this bug is so bad that it kills the entire experience for him. This is how people react to things they don't like: if they enjoy something for 9 hours and absolutely hate the 10th hour, most people will just say they hate it.

As for contacting you first, how easy is it for him to contact you? Did you say anywhere in the game that you all are happy to hear suggestions for improving the game? Also remember that for most users, the App Store is the only place they will interact with you. That's the model. Even if you had said in the game itself that you welcome suggestions and how to reach you, that may not be how users think about you and your game.