My previous relationship was with a guy older than me, and parts of it were really, really good. for example, If he's a lot older, he doesn't have much stamina, so he spends a lot more time on other things.
Then there's the generational thing. My ex and I used to kick ass at Trivial Pursuit partly due to being from different generations. He knew all the military and history and all the sports and a lot of the entertainment stuff, and I knew the history and literature and whatever else there was in that game. We were a formidable force that our team mates still talk about with actual awe.
Another thing that was both good and bad was that he had a lot of stories!
A bad thing was that he actually was a bit too adoring. Almost smotheringly so. I don't need a lot of attention and it sometimes drove me mad.
Other downsides: his taste in music. Ugh!
His love of old black and white movies, constantly.
Also, believe it or not, he drove too slow!
In my opinion, if you want real maturity, start with a 26 year old. Good age for guys, I always thought!