Agreed for the first part - and the motion capture of 4 and onwards greatly enhances the emotions you can see out of the faceless character. The fist clench in the legendary ending is what I keep coming back to, it's such a little thing but if you can read body language, and know Chiefs character doesn't show emotions externally, you know it means a lot.
I'd be interested in some non covanant and promethean enemies too, also non-human (I'm not really down for fighting human rebels). Like that race that crash landed on one of the Halos in the terminal videos. If they achieved space faring so much earlier than the covies or humans, if they havn't wiped themselves out or reset themselves they must be very advanced by now.
And I also believe the forerunners are still alive, what are the chances they saved every other race but no members of their own species? They may just be hiding away not bothering other species.
Well we know they're alive, there's the Didact for one.
I don't think we'll be fighting any actual Forerunners at any point though, other than maybe the Didact.