There's nothing wrong with 7/10. However, in gaming, it means it's not that pleasant. For example, in a 0 to 10 scale, the average would be 5, but in the gaming world is 7. Grades below it means the game isn't good, and goes worse every lower grade; grades above it means the game gets good every point further.
It's a bit hard to understand where test grades are from A to F, but in places where they are scored like in most games magazines and website, such as mine, is easy to get used to it: 6.5 in a test means you'll have to try harder, because it's not good. Same with the games.