I have very direct insight into this question.
You see, I was 32 and my girlfriend was 18 when we met. I am now 33 and she is 19, and it is the best relationship that I have experienced. I can hear nay-sayers now--"this doesn't mean that the relationship is good"--but I'll say this: she understands me in ways that are almost frightening. And I her, as we have both put a lot of time and effort into contemplation, and apparently we think about different things than other people.
I'm not immature, nor am I a playboy or party-boy. Nor a boy of any sort. She is brilliant--not "for her age," but truly so--and we get on extremely well.
For those mentioning "stages of life" above: I appreciate and understand the argument. I even held this position and so fended off my great appreciation and interest and admiration for her for a couple of months, on this premise. However, maturity, emotional, and intellectual compatibility can trump this. Additionally, she was largely raised by people in my parents' generation--thus we have been exposed to similar lines of thought growing up.
Ansley: your efforts in going after your guy mirror those that I fended off for a while before coming to the conclusion that I would be turning down happiness and being with a wonderful person. I can appreciate this from both sides now.
Having such a large age-difference between the two of us is not what I'd have planned, but it can happen. And it can be exceedingly rewarding for all involved.