I've been catching up on the changes to multiplayer and the meta game stuff they added and the only things that really concerns me are the kill streaks, perks and the flag carrier indicator. Kill streaks and perks typically have too large an effect on how people play and the flag indicator takes away a lot of tactical situations.
I'm not a fan of unlocks, but eventually you'll have everything you need unlocked and if they keep things in line, things should unlock relatively quickly.
Kill cams reveal snipers, so in an ideal situation, it wouldn't exist but bullet vapor trail in Halo seemed to do the same, effectively enough. I don't think it will have a huge impact.
I'm not sure how the see through walls ability will play out but from the video it looks like it obscures things enough to not be something I would use.
I think the biggest difference between modern Call of Duty and Halo is the gameplay and from the videos I've seen the core gameplay appears to be intact, so I'm still optimistic that I will have a good time with multiplayer.
I'm not sure why I posted this in Halo GAF instead of the Halo 4 OT but there it is.