I'm 26, my other half is 41. It's only other people who bring up the 15 year age gap - we never sit together or make love or chat while thinking "Oh my god there's 15 years between us". We just click, we're best friends as well as a couple. We have different interests re hobbies and the like, but that's nothing to do with the age difference, and everything to do with us being individual people with individual interests, we share the same opinions and views about most things. I must admit to being shocked when he told me his age, but again it wasn't because there was a gap, it's because he looks younger, I had thought he was in his early thirties.
For us, it's not about age, it's about character.