When I was old enough to play video games, it was the era of Game Boy Advance and GameCube. Granted, my grandma has a N64, but not a whole ton of games. So the first Smash Brothers game I actually played was this, and I loved it. My brother, sister and I would play this game for a long time and even make our own stories with it. I made my own stories with it when I played as well. I recall making one where Kirby wanted to be a Pokemon or something like that. Speaking of Kirby, I'd go into training mode and absorb everyone to see what Kirby turns into for each character.
I might be seeing this through nostalgia filters, but I love this game, as well as Brawl and Wiiu.