So let's get the obvious questions you may have out of the way. First, yes, it hurts the back. After a little bit, your muscles in your back get exhausted and the curve of the spine begins to ache. So it's not something you'll want to take your time at. Second, I'm rather thick so it makes my jaw sore. If you try to suck on one of those cardboard paper towel tubes, you'll get an approximation of the difficulty of taking much of me orally (I'm slightly thicker). So when I'm sucking my own cock, it generally is for show or for the novelty of it, not for long-term pleasure.
That said, if you tell a person that you can suck your own dick, chances are they will want to see you do it. I've been asked by women, gay men, straight men, groups of people, and so on. There is a perverse pleasure in seeing the effect of what the idea does to people. Then when you show them...
They ask to hold it, they get in real close to see my lips around it, they absentminded drool or fondle themselves while seeing it. They all comment. I've given shows to a group of people before. And even though I am only able to get an inch or two in my mouth, the feeling of having my cock worshipped is a strong intoxicant. "Yes, that's right. My cock is so huge I can suck it myself. Look!"
I don't think anyone would believe me if i told all the stories i have about licking and sucking my own cock in front of people. There have been some strange situations in my life. One story: I dated a woman so impressed by the fact that i could do this that one night after a pitcher of blue kamikazes, she blurted out to her sister and her two friends in attendance that "X can suck his own cock". They immediately demanded proof. We went into the bedroom, I stripped and sat on the bed. The "oohs" and "aahs" changed as i wrapped my hands around my cock and stroked it to get hard to "oh my gods" and "holy shits". My girlfriend all the while saying "told you he was huge". Once hard, i got cocky, waving it around bragging about how long and fat it is ("Ever seen a cock this big? This heavy?"), then bent down and took the thick spongy head into my mouth. You could hear my girlfriend muttering "fuck yeah" as i two-fisted my long shaft and sucked on the head of my cock.
I didn't orgasm that evening. Like I said earlier, it is a painful exercise. But I did get up from the bed, hard dick sticking straight out, and walked into the kitchen for a drink. I remember relaxing nude in front of them all evening as they made glances, bad jokes, and such at my lingering half-erection. It was one of those points in my life when I was proud to be so large. I really enjoyed showing off as well. This is my secret fantasy. To find that level of desire over it, lust for its size, knowing it has power over someone. I've often said I will worship the entire woman I'm with, so long as she worships my penis. Fair trade I'd say.
Before my girlfriend and I broke up, I ended up having sex of some kind with each of the people in attendance, including her sister. A threesome with two sisters is a pretty rare experience. I'll never forget her sister squatting over me, poised, and nervous while my girlfriend comforts and tells her to not worry. Something I wouldn't have had if not for my beautiful, long, thick, heavy, horsecock.