I think it would be a good buy if he likes the titles available for this console. Personally, my boyfriend and I are 21 and haven't stopped playing since we both bought Pokemon Black 2. Other classic titles like Legend of Zelda:Ocarina of Time, the Mario franchises, etc. are definitely a worthwhile try if your man still yearns for the good old gaming days too. The nice thing about the 3DS is that it can play both DS and 3DS games without a problem.
If you're also looking for a portable system that plays movies, has HD capability, has more "mature" (so-to-say) game titles (i.e., Call of Duty, Assassin's Creed...), etc. then you may want to also look into the PS VIta.