I agree that the number alone is useless. This is why I like thorough reviews that try to be as objective as possible. The number gives you an idea of how close to "perfection" they found it to be from their perspective, and the text should give all the accompanying reasons for why that is so, and why it didn't get full points.
i.e.
I'd rate the Graphics a 5/10.
The score is right at the halfway mark, because the graphics are just okayish. They get the job done and everything looks like what they should, but they don't really bring out the world or the characters. Everything animates stiff and roboticly, and don't convey much emotion or action. There are a very limited number of animations too; the character's sprites hardly ever reflect the actions they're currently performing. Like when they lift up an object, you'd expect for the character to look like they're carrying it, but they're just using the same walking sprites with no change, with the object just floating above their head.
i.e.
I'd rate the Graphics a 5/10.
The score is right at the halfway mark, because the graphics are just okayish. They get the job done and everything looks like what they should, but they don't really bring out the world or the characters. Everything animates stiff and roboticly, and don't convey much emotion or action. There are a very limited number of animations too; the character's sprites hardly ever reflect the actions they're currently performing. Like when they lift up an object, you'd expect for the character to look like they're carrying it, but they're just using the same walking sprites with no change, with the object just floating above their head.