Okay... here's all my thoughts poured into one post.
1. **** NO PUBLIC CHAT!?!? Damn it, bungie, get with the times!
2. H2V will have EVERYTHING (maybe not, maybe a few minor things like diff. shaders, textures, etc.) that H2 Xbox has. Alright!? Thank you.
3. If you look at the gameplay videos, you'll see that H2V WILL have ragdoll physics. W00t!
4. I am VERRRRRY glad that H2V will be able to sync maps over the internet, without you having to have the map itself. Then you can just see "oh that map looks cool, 'super_duper_awesome_mod_2' I don't have the map but it looks cool, let's join it" "wow this map is awesome"
With the online syncing, you can also have a scenario something like "well, I just made a map and am excited to play it, but it'll take hours for people to see it and download it halomaps.org, and I want to play it with people now! Oh right, they can enjoy the map without having it through server syncing-they don't even need to download it!"
5. H2V had better have text chat. Suppose your uber mic broke and you have no way to communicate with your teammates? Besides, some things can only be said over text-you can't say OMFG and sound cool with voice.
6. There might be new weapons-at least I hope there are. Bungie said there wouldn't be, but hey, they said you couldn't play with people on Xboxes, and now they're saying if you pay (or already pay for Xbox live) then you can play between platforms.
7. Bungie said you will not be able to play coop with people online. BUT, like that guy said earlier about the coop teleport and stuff in HPC, Bungie came close, and since maps can sync over the net, and they also lied about playing between PC and xbox, it's a possibility, and i would LOVE it. But, I highly doubt it.
8. You'll absolutely be able to play as an elite or spartan online. Yay!
And finally I doubt there'll be different melees but if there are that'll be cool.
Whew!