I am 37 and my girlfriend is 22.
The age difference was more of an issue for me, at first. I didn't like the idea of dating a younger woman (and I had preconceptions about older guys with younger chicks, that turned me off the idea). In all honesty, I usually prefer women who are my age or older. I like their independence, intelligent chat, rich life experiences, and so forth.
This time, despite my reservations, I took the punt, because she was different to me in every way. I am glad that I did, because our different life experiences and outlook actually enrich each other (although it helps that she is intellectually mature and I am still incredibly juvenile).
In all honesty, the age difference doesn't come into it that much, aside from the fact that with 15 years difference we have different cultural experiences. Still, the good thing is we have lots to share and always learn new things. Makes it much richer to have different experiences than talking about stuff with someone from a similar age group, where you have a good chat, but don't really learn anything new.
I have deliberately avoided the obvious physical aspects. This side of the relationship goes without saying.