When I first tried pot, back in the mid 60's, I did so because I was interested in experiencing altered states of consciousness. I was in high school, and had gotten into the writings of Timothy Leary and other "psychonauts". At that time, while I did not experience hallucinations, I did experience both spacial and temporal distortions. The temporal distortion was most interesting, and it's something I never forgot. My cousin and I had just smoked, and we were crossing a road. I experienced that crossing as if it took years to get to the other side. As far as I was concerned, several years passed before I got to the opposite side of the road. Subjectively, that is how it felt. Time itself was definetly distorted, or altered, from my subjective perspective.
The spacial distortion I experienced on a separate occasion is a bit harder to describe, but it basically amounted to seeing my environment from what might be a cubist perspective. I was driving a car uphill. Everything flattened out, and as we drove up, it was as if the scene in front of me flattened out and turned two dimensional from a normal three dimensional view. (Edit: I just realized I can better describe the spacial distortion I experienced under pot. Driving a car up a very steep hill means you are moving both forward and upward. Suddenly, the scene before me flattened out. The car was no longer moving forward. Rather, it was as if we were in an elevator, and the car was going straight upwards, no forward motion, till we got to the top of the hill. So the spacial distortion involved turning 3 dimensions into 2 dimensions. Again, not a true hallucination, but a distortion of normal space.)
Those were the only two times in which my perspective, or experience of reality, were altered while under the influence of pot. Both experiences happened in the first few times I smoked, and things like that we're never to repeat themselves. Not true hallucinations in the sense of seeing things that weren't there, but very cool nonetheless. And again, the temporal experience was fascinating. Stretching out the subjective experience of time from what actually passed, maybe 10 seconds to cross a road, into years instead, was thought provoking. And I was interested in having experiences that would somehow "alter" reality, and have always been a proponent of "cognitive liberty". As long as I am not harming myself, or others, my state of consciousness is my business, not the state's.