Random thoughts so far:
There is at least one thing that will still distinguish Halo from Call of Duty, thankfully: no aim down sights. So you will still have the traditional encounters in matchmaking, which is still the most important part of the game that 343 could leave intact. Well, I guess that's assuming people don't mind AA's. That leaves Gears being the main 3rd person shooter, Call of Duty the ADS FPS, and then Halo the non-ADS FPS.
The perks system, which I don't really care for, should at least become a non-factor over time as everyone maxes out their armor/weapon upgrades. I do find it a bit odd that 343 is implementing random power weapon spawns to prevent the better/veteran players from taking advantage of the newer players. But they are also adding these perks that will essentially give the players who have spent more time in the game an advantage of the same new players.
I can deal with the random power weapon spawns, because I prefer the focus of the game being on combat and not on how soon a person can get their hands on a power weapon for the easy pew pew kills. "zomg look at my sniper highlights - i'm so good!" But it will remove the strategy involved in fighting over the power weapons and I think most people will dislike that. I definitely can envision scenarios where you're chasing someone down and they randomly find a rocket launcher, turn around, and kill you, instead. Those type of situations are going to suck. Whether or not random power weapons will make it easier for the casual crowd or not, having power weapons set as static spawns is the only true fair option. I'm not a big fan of randomness in game. It makes things even more frustrating when you're on the losing end. Power weapons need to be balanced by the other weapons and then it wouldn't be a problem. In Reach, they weren't.
The instant spawn thing is probably the biggest eye sore for me right now. But, it also seems like something that will be the easiest to alter after release if it doesn't work. And I imagine it will be adjusted. Random spawns have been a big problem in the past games, and I just don't see any way that adding instant spawns to the equation is going to improve the issue. I guess I'll wait and see.
Along the same lines, if forerunner vision turns out to be a pile of crap, it too can be removed. Although how long did it take for AA's to be adjusted in Reach? /sadface