I was 20, and I married him out of a combination of "total infatuation" and "cold, hard practicalities" (he was from overseas and would have had to return after uni).
I was divorced at 32.
Do I regret it? Not really! In the sense that I like my XH, we're still friends, and will probably always be. Having lived through some really tumultuous times together, he's that one friend I can tell absolutely everything and who will never look down on me, having seen me at my lowest and worst. And: I'm genuinely happy that this has meant he has had the chance to build a life, a career, and a family here.
Was it good for me? No! Not even remotely! My timing - both in terms of getting married and getting divorced - have made my life awkward and out of sync with my peers. When my friends were dating and figuring themselves out in our twenties, I was "the married one". In our thirties, I was the "single and fun" one whereas they had started to settle down.
Would I recommend it to a friend? Never in a million years! We typically simply don't have all that much of a clue of who we are and where we're headed when we're that young. And I suppose shared goals, at the end of the day, matter so much more than pure infatuation when it comes to making a marriage a success in the long run!
That said, I'm now 40 and a corporate executive - most of my peers are men in their 50s, who are either divorced or on their 2nd or 3rd marriages. At least I get to "fit in" over "fun" divorce stories ... it's something, I suppose?