OK, I've hypnotized, been hypnotized, and used self-hypnosis. I have no doubt at all that it is "real" but might disagree with some about what it actually is: what's bunk and what's genuine.
As a kid, I read a book about how to hypnotize, did it on my friend, and it worked. Of course, I can't be 100% sure if he was humoring me or if he was really in the classic hypnotic state, but I eventually concluded if they are indistinguishable, perhaps it doesn't matter.
When I was college age I asked to be hypnotized, and requested that I be led into a sexual fantasy and a hallucination (I was a horny kid). My friend did it with two other friends watching, and when I was told to have fantasy sex in bed in front of them, a curious thing happened. I really, really didn't want to embarass myself in front of my friends by having sex with a pillow while they watched. I knew exactly what was happening and never fantasized a girl in my bed. However, I felt compelled to act exactly as if I believed I was really doing it. I pleaded once with the hypnotist "please don't make me do this," but he insisted and I complied, although half-heartedly. Another thing he tried to make me do was hallucinate that there was a chicken in my lap. The result was that I merely imagined there was a chicken in my lap, but I never actually hallucinated it. However, like the sexual fantasy, I behaved as if the hallucination was astonishingly convincing.
So, my hypothesis is that hypnosis puts one in a very compelling state of obedience, but not a state where one is capable of vivid hallucinations, super strength, telepathy, super recall, or any such expansive capabilities.
I've also been told by my parents they were at a hypnosis show, and my father was made to do several humiliating acts before the audience and to forget them. He always professed no knowledge he performed any of the acts. One could suggest that he was too embarassed to admit he did them, though if he found them that embarassing, wouldn't he have refused to do them in the first place? I have yet to see a hypnosis show where a subject refused to do some humiliating act he was ordered to do by the hypnotist.
My self-hypnosis experiences are inconclusive except for being effective for relaxation.