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The lyrics
- Lack of substantial / sophisticated messages in the lyrics.
  - Keith Richards (of The Rolling Stones) - "So many words, so little said." (Source)
- Lack of variety in the messages / topics of songs.
  - Keith Richards (of The Rolling Stones) - "So many words, so little said." (Source)
The accompaniment
- Lack of sophistication in the melodies
  - Keith Richards (of The Rolling Stones) - "What rap did that was impressive was to show there are so many tone-deaf people out there. All they need is a drum beat and somebody yelling over it and they’re happy. There’s an enormous market for people who can’t tell one note from another." (Source)

punching - A technique used when recording a track where the rapper will start rapping part-way through the song, and then multiple recordings of them rapping will be stitched into a single track. This allows the rapper to correct mistakes more quickly. It's criticized by some people because it seems to make it possible to record raps that the rapper isn't actually able to perform live, because there's not enough gaps in the rap for the performer to breathe or because it's simply too difficult to get through the song without making mistakes.