When I first finished Halo, I couldn't decide what I thought about it. Yes, it was a good game, it had action, it had great graphics, it had everything a good First Person Shooter should have, but that's it, it was only good. The gameplay was often repetitive, it was often so boring that you'd stand up and start screaming at your TV, but the simple truth was that it wasn't a great game, only a good game.
Halo wasn't the first ever First Person Shooter game, so it wasn't original in that sense. It wasn't a particularly big game that would keep you occupied for weeks. It wasn't the first game to have a weapon which could home in on enemies, nor was it the first game with vehicles or rocket launchers. It simply combined many elements from other games, and it was praised for doing so. It didn't have the originality of the first Medal of Honour game. Halo was never particularly immersive either, it was just a game you could pickup and play. Personally, I think that Halo was so hyped, purely because it was one of the first XBox games. It's game play wasn't particularly good, and everything you could do in Halo, you could do elsewhere too.
Halo is often said to be the benchmark for modern First Person Shooters, but I have seen many better games. Killzone (though I'm not a fan) is a much better game, as is Resistance: Fall of Man (which isn't particularly good by PS3 standards). The plain and simple fact of the matter is that Halo has been so overhyped that people don't even judge it anymore. Nobody highlights its flaws, its lack of believability, it's lack of realism. Recharging shields made the game far too simple, a skilled player would hardly ever die. Nobody ever accepts that it isn't perfect, and nobody ever credits other games with the credit that they deserve.
Personally, I am happy to see the last game of the Halo Trilogy come out, maybe it will finally be forgotten after Halo 3 is released, but I ain't holding my breath.