In my younger days, I'd dated anywhere from 4 years to 10 years older seriously; even older less seriously. I generally got along with older folks, and I was looking for someone with mental maturity. I didn't find it, presumably because these folks were looking for someone who was immature. I dated women who had been through experiences that should have taught them better (e.g. how to communicate in a damn relationship), but they hadn't.
With an age gap of around 4 years, you're not going to find much difference in mental maturity--people 4 years older or younger than me kind of think like I do and are around the same stage of life. With a much larger age gap, you may not find much difference in mental maturity, and you may also run into problems with being in different stages of your life.
But maybe you won't.
Nobody in the relationship should give a damn about what the outsiders think. .. at least, ideally, they shouldn't. I'm in an interracial thing now; if I cared about what other people think, I'd be depriving myself of a good relationship.
Moreover, our cultural differences could have impacted our relationship, but they haven't. Age differences could be treated in much the same way.