Nobody questions whether it takes development time and yeah I am fine with a trailer because its what they should have done last year but give me a break the biggest games getting big showings at the biggest show is not exactly a strange idea. It is what happens. I am saying show it off in a meaningful way. Meaningful doesn't have to be a 45 minute demo.Nah...campaign vertical slice takes away from development time. Their campaign team is using all this extra time to focus on finishing it. Multiplayer was much further ahead...and still hasn't been talked about. Multiplayer and Forge is what will give Halo legs. Multiplayer is in flighting and behind the scenes, people think 343 has something there. I'd like to see another campaign demo myself but if they released a game that feels like it could use another month of polish, making a vertical slice will seem like a bad decision. A campaign trailer cutting together the most polished gameplay segments isn't a bad strategy.
Reminder: vertical slices are never where the game actually is in development. AAA devs will tell you these games get glued back together in the final 6 months of development. Everything before that is fake.
The expectation is for Halo to have great campaign and great multiplayer. I am sure certain people will hand wave one of the two away as not important if one of them ends up disappointing but that is the reality.