I rate based mostly on my enjoyment and sometimes how well made I think it was 

10 --- masterpiece 

9.5 - 9.0 --- loved 

8.5 - 8.0 --- really enjoyed 

7.5 - 7.0 --- liked it a lot, but had some issues with plot/character/pacing

6.5 - 6.0 --- enjoyed it, but didn't feel very strongly about it 

5.5 - 5.0 --- liked parts of it, but mostly didn't think it was good 

4.5 - 4.0 --- watched it, but didn't enjoy it that much 

< 3.5 --- the worst thing I've ever seen