From what I've seen based on the demo, I think ODST is looking like everything Halo 3 should've been from the very start, apart from the ODST part obviously. I don't really think Halo 3 is that much of a great game, but this one is looking to be much better, pushing the engine to the potential I saw in it. The open world, the interactive features with the visor, everything is looking really good.
I don't know if I've got this right but isn't stamina a form of damage resistance? Like the less stamina your character has the more likely he's going to get wounded. Just a new feature I'm confused about in Halo 3 ODST. Anyway I love the fact they're bringing health packs back, something that should've stayed in Halo from the very beginning. The Pistol looks like a combination of Halo 1's and Halo 2's pistol, it has a scope but it can also fire rapidly. I don't know how much damage it does though. I heard you couldn't pick up Covenant equipment, but in the demo I saw a lot of "press RB to pick up Plasma Rifle" dialogues, so they could be lying there. Unless they meant equipment like the bubble shield. And to be quite honest equipment never really interested me, so that wouldn't bother me if you couldn't use it.
I'd appreciate it if they implemented more stealth into the game but then again I haven't seen much of it so they probably have. Firefight mode looks pretty cool, and Bungie were very clever to hide most of it's features, and showed some gameplay of it using the theatre mode. However judging by the fact that you can get Sergeant Johnson as a playable character in Firefight if you pre-order this from certain shops, I'm guessing there's a ton of characters you can select, along with more features. After all, we did see all this from theatre mode, and not Firefight mode.
Something else I noticed - the return of Red. Sorry, it's my own nickname for one of my favourite weapons in the Halo universe. I am of course talking about the Brute Plasma Rifle. Your character won't be so "stiff" this time around either, meaning that things will happen to make your character react instead of just stood there, and all of this will happen while you're still in first person. Nice. I'm hoping to see the return of many things from Halo 2, and even Halo 1. Things such as the Spectre and Shadow. Hopefully in driveable form this time around for the Shadow. Bungie also said that there's several ways of transport around New Mombasa, my guess is one of them could be a rail system.
Anyway there's just a tiny couple of things that are slightly off putting. The expansion is full price, something I knew would happen because Microsoft are just plain greedy, even Bungie said this is just an expansion and is not worth full game retail price. However, it does come with a Halo Reach beta, so I don't know what to do. Also, the Firefight mode uses skulls. Now I love a challenge, but I don't like the effects that some of these skulls have. For example I don't want to be playing Firefight, I'm killing loads of Covenant, then along the way the nasty surprise of Blind Skull comes in. Like I said I love a challenge so long as the challenge is only on by my choice. However it's looking like a promising expansion and I'll get it for expansion price one way or another (I usually just go to Tesco :P) and I'll be posting more impressions when I see more games.