Hopefully it will work out well for him/her. When I hear about totally dysfunctional people wanting sex-change operations, I'm pretty quick to assume they just need to get their heads screwed on tighter and quit blaming their problems on stuff like being in "the wrong body". But when someone who has a history of holding down good jobs and staying out of trouble says they feel they really need a sex-change operation, I'm inclined to take their word for it.
The interplay between chromosomes, hormones, brain development, and genital/gonad development is very complicated and no serious medical researcher claims to understand it all. I'm sure things really are out of whack in some people who appear physically normal, but the dysfunctional ones need to get their acts together first, because the surgery doesn't fix dysfunctionality -- just halfway fixes the sense of gender misfit. A dysfunctional man who gets a sex change operation will just be a dysfunctional woman, and if you're dysfunctional it really doesn't matter what sex you are. And in many cases, I think fixing the dysfunctionality will cause the urge for a sex change to go away.
No, he'll still be a dysfunctional man. After the operation, he'll just look a bit different, and have less money.