I'm going to toss in my LSD experience.

What's most important is that you don't do it unless you're around people you trust, you're in an area where you feel safe, and you're in a healthy frame of mind. If you decide to try it, you should probably start with a small dose. I went with the "Jump in the deep end to learn how to swim" method. It was an incredible experience but overwhelming to such an extent that I don't ever want to go through it again.

Yes, you can hallucinate on acid, but it takes quite a bit. The first time I did acid, I watched a bunch of cops cars pull up, and one cop came over to me and started asking me what I was on while shining his flashlight in my face. I couldn't get up and I could barely talk, so I mumbled, "Nothing." My buddy laughed and told the cop I was on acid... at which point the cops morphed into a guy I'd seen earlier, who had a glowstick around his neck, but definitely wasn't holding a flashlight. I looked back towards the cop cars. There were none. Needless to say, I'd done way too much acid that night.

Fractals are a normal part of trips, and they are gorgeous. Seeing things "breathe" is fairly common. As one of my friends said during her first trip: "Is the poster breathing? I know it's not, but... is it?" She and my (also tripping) husband then had a long, in depth discussion about whether or not the poster was breathing. Later that night, her boyfriend tried to get in a fight with her and her response was to sit on the ground and giggle nonstop because the ground looked like it was made of octopodes (your brain can make all sorts of patterns out of the fractals).

Acid can affect all of your senses, but it hits you hardest visually. It mostly just amplifies everything else.