It was absolutely life changing for me.
I had a really unusual nose, the kind you need seriously high self esteem to carry off - but I was massively emotionally abused/bullied by my family, so my self esteem was very low. I was also primed to be vulnerable to bullies by the abuse, and having that nose just made me a really obvious target.
I look back and I think I lived every single day of my life in fear of being laughed at/verbally abused, because it happened so often, well into my adult life. Because my self esteem was so shot, it was nigh on impossible for me to fight back against the bullies who would pick on me, so I just suffered.
At the same time, I was seen by many as a strong person with a strong character, which is also true in many ways. And I had this belief that I just had to live with my nose the way it was, that it would be weak to change it, that I wouldn't be me any more somehow, that I should love myself the way I was, that having it done would be agreeing with the bullies that I was ugly and freakish.
So it took me a very long time to actually do it. OMG, if I could turn back time, I would have had it done on my 18th birthday. A decade on from the op, the difference it has made has been amazing. I don't feel worried when meeting new people that the first thing they'll notice about me will be my nose. I don't have to brace myself for the jeers walking past a group of teenagers - they don't even notice me now. I am no longer subject to complete strangers hurling abuse at me or feeling entitled to comment on my nose in a pejorative way, right in front of me.
Most of all, I am not defined by this extremity on my face any more, I'm free just to be me, the person I actually am, and always was.
No one would think that the nose I have now is the result of a nose job, because it's not perfectly sculpted, it's not particularly neat or cute. It's just not weird or extreme like it was before, and it fits my face, which it didn't before. I did a lot of research on surgeons and interviewed at least half a dozen of them, and chose the same place in East Grinstead mentioned upthread, one of the fantastic team at the pioneering maxillo facial unit there.
Very, very happy with the results. Of course it didn't make all the issues from my past go away, that's another job and another story, but it did relieve me of one huge problem in my life in one fell swoop. And I have never, ever, not for one nanosecond, regretted having it done. Never missed my old nose at all - I used to think it was somehow such an important part of me, one friend at the time actually said "but it's like part of your essence"(!) but it totally, absolutely wasn't.
I was worried it would be a betrayal of myself somehow, but actually it's just about the kindest thing I've ever done for myself.
So if you want to do it, do it!!