This was my first MMO and still holds a place in my heart as the best. Maybe it's because the servers were small. Good and bad things you did traveled by word of mouth and there was an actual community to be a part of. I remember using the tiny, archaic map given in the booklet that came with the game to map out my routes, almost all of which were wrong, since roads only went so far. This forced exploration. There were so many little cool camps of enemies or points of interest that weren't mentioned (to my knowledge) in the game. I remember trying to escort a friend to Qeynos simply because we wanted to see it. We passed over mountains, got killed by Gertrude, wandered aimlessly in circles through forests, met and chat with others exploring as well. Exchanging directions, trading items, sometimes banding together for mutual benefit.
I guess for me it wasn't so much the game, it was the world and the community of players within it. Everything was personal. Everyone (mostly) was personal. You had to be, because your name being mentioned as a ninja, trainer, troll, etc. could really effect your status. Maybe my judgement is clouded with nostalgia.
So, why do you love this game?
(and is it worth coming back to?)