Master Chief was great in the first two games, but he was not what made Halo: Combat Evolved so great. It was the gameplay, the setting, and the presentation. It was the simple but dynamic AI and the element of tactics and meaningful choice introduced with the weapons and weapon swapping system, that kind of thing. As much as the PC guys are going to hate me for this, Halo was much more interesting to play than your standard 'twitch' shooters of the day. That's why I get annoyed when people (ahem, Yahtzee) call Halo a standard, run-of-the-mill shooter. It set the standard. For those of us who were actually there and playing the damned thing, Halo is the original and everything else is imitators. It's like how this generation thinks Seinfeld is just a run-of-mill sitcom and Citizen Kane is just a boring old movie.
You may say I'm rambling, but this is the kind of stuff I want to hear from the guy who will decide what Halo as a series is from now on. I want to hear that he understands what Halo was and why it was great. Master Chief was great, but he is not what made Halo great.
Then again, I thought the best things about Halo 2 were The Arbiter and the civil unrest within the Covenant (although, they should not have had the Covenant races start speaking English). I thought that was a great way to expand the story and the universe a little bit, but apparently I'm in the minority on that. So maybe I don't know shit.