Well, aside from being my favourite game of all time and having an incredible story, characters, music and so on, it's also the first adventure game that I played. Without GF, I would have never learnt to know Broken Sword, Monkey Island, Gabriel Knight and so many other titles. These games in turn turned my interest from anime/manga to western cartoons and comics.
Through GF, I've also made some very dear friends whom I would have never stumbled upon otherwise.
I guess it could be said that GF has affected me so much that it has become a part of my life. I can't imagine a world where I couldn't hop online and talk about the game with fellow fans. We're very lucky for having each other and this community. After watching several excellent animated movies (The Prince of Egypt, The Road to El Dorado and so on), I tried to find forums and fansites devoted to them, but it looks like I came some five years too late. Everything is dead and everyone has packed their bags.
Let's keep the GF spirit up and make sure that there'll always be a place for fans to hang out.