As a player of the earlier ones...
I really liked the addition of the long notes, as it made the gameplay more variable, altough, removing my finger from the button at the right time was hard :P
The graphics had a huge improvement from the earlier ones, I like the balls more than the vertical lines, that were hard to keep track of.
Altough I like this game, I liked the earlier ones more. This one didn't have any songs that got my pulse up, and they all were too easy. Even in Hard with speed 10+ Also, 4 songs doesn't seem to be enough.
A way to listen to the songs before playing them, would be a bonus :P
I liked the old songs more. If you're going to do a fifth one, I would like to see the comeback of the old songs, with more difficulties :P
But, I won't punish a game for not being as good as it's earlier ones. Hence 9/10 and 5/5
All in all, it was, and is still one of the best rythm based games on Newgrounds.