I find this post puzzling, really.
The Halo series has everything. Storyline, run and gun moments, sniping tactical moments, close combat, great variety in weapon combinations, effortless controls for a console FPS, nicely adapted difficulty, varying enemies, intelligent enemy squad AI, hilarious moments from the NPCs, changing environments, great vehicles with abundance, an epic feeling, intelligent weapon systems (you can't carry a thousand like in other games), imaginative and balanced weaponry, and cooperative play.
The game is great fun, short-yes, graphically not special-true now. But the underlying gameplay is both user friendly and replayable - less staged than so many other games that always play out the same....
I could go on.