Halo 3 is nearly five years old, and I think your memory of the first XBox is overly rosy.
'intense and claustrophobic' sounds like 'on-rails shooter' to me, so I really hope that's not representative of the game. There are lots of games like that already and more in the pipe. I'm very happy to know that the demo is a compressed version of part of a level.
It is, but it looked bad when it first came out. I said that at the time it actually came out, so it is not anything to do with how games look now. It is graphically better than your typical Xbox 1 game, but there were places in that game where it just looked ugly. It wasn't exactly on par with the best looking games at that time.
Well, it could be more influenced by CoD, and I don't know if that is necessarily a good thing, but there was certainly something about it that interested me. And more so than previous Halo games.
And speaking about Ubisoft, one game I am looking forward to is FarCry 3. Again, like halo, I was not particularly interested in the franchise until seeing this new game. I'm not sure yet how good the gameplay will be, but in terms of the characters and story, it seems really quite interesting. The characters are believable. The dialogue and voice acting seems top-notch. They're trying to bring a sense of real insanity and madness to the island and I think they have nailed it.