Disclaimer: I read visual novels for the story. If you have a good story, you have a good visual novel. With a poor story, no amount of artwork or music can help. These are only guideline judgement criteria for my score; I may choose to ignore it in some circumstances.
Story (40%)
– Choices
– Concepts
– Endings
– Emotional Effect
– Overall Plot
– Setting
– Writing Quality
Characters (20%)
– Player Or Main Character
– Side Characters
Art (20%)
– Backgrounds
– CGs
– Character Sprites
– Videos
Audio (10%)
– Music
– Sound Effects
– Voice Acting
Other (10%)
– Extras
– Interface
– Navigation
Also, when applicable, I will also be looking at Value For Money.