Halo is a good game, but there is nothing about it that puts it above others in the same category.
The Good:
Polished, balanced, and steady gameplay and an intriguing storyline. It gives you a reason to fight your enemies.
Great music that goes with the gameplay.
The Bad:
Halo is an overrated game, and is far from being the extraordinary masterpiece it has been played out to be.
Even on the harder difficulties, Halo seems nurturing and forgiving. The only real challenges are brought about by multiplayer against other people.