I do feel like selling the "interesting" part of Hallucinogens as the visuals is hugely under selling the entire experience. Feel like that's the LEAST interesting part. It's the ability to step into a different experience of reality / head space that's simultaneously engaging and terrifying.
Strong synesthesia between sounds, words, taste, colors, textures: e.g. distinctly "feeling" the word "blueberry" as a taste and color. (Psilocybin)
Spatial reality distortion that's stable over a trip (Psilocybin). Linked with time distortion "literally feels like we've been walking for an eternity where on the previous day it only took 5 minutes"
Coming "closer" to reality and seeing it at a higher "frame rate" (LSD).
Complete disassociation from your normal reality and being projected into a complete different spatial relationship to existence (Ketamine).