Going back to the first post in this thread.
Halo 4 - Graphics great, campaign great, story great (ending copied from COD though :/ )
Although Halo 4 will undoubtedly prove to be one of the most if not THE most popular Halo game, the only reason for this is because the developers have simply looked at Halo then looked at COD and tried to merge the two together to try and make it more inclusive.
Halo has always lagged behind COD in sales because it doesn't appeal to the mass market. Halo was always harder than COD and players who started playing and couldn't do well online would get frustrated and simply stop playing because it wasn't fun for them and they couldn't level up (because to level up you have to win games). Now developers have tried to make the game more inclusive and easier to play, getting rid of ranking systems based on skill and more on how much you play is a major factor...you might as well not have any ranks at all and just have amount of hours played next to your gamertag.....
This game is no longer the original Halo, it has been diluted down so much. Unfortunately I have a feeling Microsoft were more concerned about making money than making an iconic game, which is fair enough as that is their job!
I feel like Halo 3 was the last real halo game. I'll still play Halo 4 no stop, but its just not the same!