Low numbers are bad, high are good.
It’s not bounded and can go negative (so far things have stayed between -20 to +20).
0 is spending the equivalent amount of time looking at a mono-colored (non-papered or -patterned) wall.
10 is perfect. An example 10 is the 1977 version of Star Wars.
So my 1 through 10 should match up pretty well with other reviewers who use 1–10, is the idea. But some things are just off the charts. For example, I’d rate Birth of a Nation in the negatives because it’s worse than nothingness.