My husband is 12 years older than me (we got together when we were 22 and 34, been together 8 years). There's no reason that the age difference should be a problem, but there are some considerations...
I think at first, for us, the age thing was superficially more obvious than it is now - meaning that at first there was a lot of "Oh, my god, you were only 6 when I went to college" and differences in cultural reference points. After a while that stuff dropped away and became less important. Then he started getting anxious for a child... his dad was 54 when he was born, and died of old age when he was 19, so he didn't want to repeat that for his kids. It took a while before I was ready for one, and I think what eventually made me ready was actually having the child, and growing up because of it. So that was a timing issue because of the age difference. Another issue will arise when we get older: I'll be middle-aged when he's getting to be elderly, and I'll likely be widowed early.
Just some things to think about... they didn't bother me enough to not be with my wonderful husband, but if you're talking a life-time relationship, you may consider them. I do also think that our relationship is enriched because of the age difference too - it makes our perspectives different, which keeps life interesting.