Unlockable Armor will have in-game effects.
This has been talked about before, but Frankie confirms it, albeit in a roundabout way:
"You will have a wide degree of control over your appearance, of course, but as we have hinted, there will also be elements of your ability and performance as a Spartan IV that you will have some control over, that will actually impact your gameplay experience, although it should be noted this will not allow players to arrive in a game session with what are traditionally called “power weapons” or a massively asymmetrical advantage over opponents"
This could possibly mean that players may be able to customize the weapons they start with, based on the armor they have unlocked. I don't think this will impact the game massively, as there will most likely be an optimum set of weapons/abilities which can dominate the others. Once players figure this out there won't be much variation at the start of the match.
There's no beta.
Some will be disappointed that 343i have decided not to release a public demo of the game, however, Battlefield 3 sales took a huge dive after wide-spread criticism of it's beta, so maybe 343i are playing it safe.
Armor abilities and Equipment
343i have described this part as 'the next logical step' which was built around the successes (and failures) of previous games. What where the successes and failures? Well from my perspective, some of the equipment in Halo 3 could be deemed a success, when it was treated like a power-weapon. However placing power drains next to respawns did seem to be a way of helping players who were lesser skilled. As for previous failures, it seems fair enough to say that armor lock won't be making a return, unless as a feature of the campaign.
Is 'ranked' coming back?
Although nothing specific has been confirmed, there was a nod in the direction of moving the playlist style back to something more akin to Halo 2 & 3.
"We aren’t going to go into detail about matchmaking systems or playlists for a little while, but there will definitely be options for traditional Halo fans to enjoy"
I'd say it's pretty certain that a 'classic' playlist will be featured in matchmaking from the start. In previous games it's been added after the community demanded it. 343i should step up and give the fans what they want, right away.
"Points Based Slayer"
This is something which stirs me, and not in a good way. In the preview video for Halo 4, there's a first-person view of a game of Slayer. What's unusual is that the points to win seem to be accumulated based on medals, or possibly damage done.
"our new implementation of Slayer will score differently than the traditional 0-50 method of yore"
This line seems to say that the old scoring system is gone, and the new one will take its place. From the gameplay footage, the first thing that jumps to mind is the scoring system in CoD games. If it is similar to this, then I think this is a massive step in the wrong direction. I expect this to be one of the big talking points in the lead up to release.
BR is Hitscan, and recoil is confirmed
Although bloom is gone (it is the will of the prophets), recoil makes a frsh appearance on the battle rifle. 343' describe it as 'predictable and suppressible' which sounds promising. With the new combination of spread and hitscan, this could be the most popular BR, at least since Halo 2.
When will we hear more?
I'll be keeping my ears to the ground, to bring you any significant developments as the roll out across the coming months. Stay tuned.