the problem with basically every rhythm game is that the charts are always switching between what instrument is being represented by the notes. it can cause a lot of confusion, especially for sight reads. it's why i like guitar hero and rock band the most, since 99% of the time you aren't playing the part of another instrument other than the rare times the charted decided to have you play like the synth part on guitar for a second since there's no guitar part going on.
playing muse dash right now and the last two tracks i've played swap between the vocals and the percussion in the middle of note strings and it's just really annoying to deal with.