I like a good challenge, and this fits that bill, but I think you expect a little too much of human reaction time; I could only get 2 apples in a row before I ran into a wall (I might just be bad, but I think making the snake move just a LITTLE slower would improve the playability).
I was going to complain that the game lacked any sort of scoring and was thus really pointless as one can't keep track of progress, but I see from your comments that you're already planing to add that; so that will be a significant improvement and actually give the game a point.
I know it may be asking a bit much, but when you do get the score system up and running, if you're able to connect it with newgrounds' leaderboards, that would be pretty awesome (give the game a competitive aspect).