This -is- the fourth entry in the series, and the difficulty has been going up steadily between iterations. I also think some key visual tweaks that were present in the Dreamy Theater releases really should have been made here too (60fps animations, shadows around the notes to make them stand out more against the background). It might help to play the game on a smaller display or sit further away from the screen.
Gameplay-wise, the note placement tend to follow paths around the screen, rather than being truly random. An issue with lower difficulties is that these patterns might be harder to see because the note count is decreased in total; if you look at some charts on the highest difficulty, the paths the notes take are a lot more discernable (
Catfood,
Melancholic). Knowledge of the song you're playing helps a lot too.