Delightfully disturbing.
I can't believe I haven't reviewed this already...
Graphics: 9. While not mind-blowingly 'pretty', you have an artistic style that is very unique and interesting...and maybe a tad disconcerting. Salad Fingers looks relatively simple (betraying the complexity of his...for lack of a better word, condition), but not in a bad way.
Style: 10. So this was the beginning of the David Firth style on Newgrounds, eh? Good start, I'd say. While this installment is the least involved of the series, it still has that eye-catching, slightly creepy feel that your fans love you for.
Sound: 9. The simple looping background music, while not creepy in itself, becomes rather disturbing when put in context with the desolate environment. Salad Fingers has a tone that, like the BGM, is not inherently creepy...but the way he talks and breathes makes the viewer know there is something very wrong with him.
Violence: 0. None.
Interactivity: 0. Movie, none.
Humor: 4. The feeling of rust against my salad fingers is almost ORGASMIC.
Overall: 10. An awesome flash that sparked the series that leaves Newgrounders craving more. Out of all of your series, this is my favorite (except for maybe Spoilsbury Toast Boy). Good job.
Ways to improve: I wouldn't suggest you change a thing. This artistic style is distinctly your own, and since the truth about Salad Fingers is still unresolved in the series, I can't say what you're trying to convey. This is perfect as it is.