The comments regarding biomes come directly from 343.I'm still really pleased at how how even Jeff Gerstmann has reacted to his time with the first four hours of the story; He's appropriately jaded enough that even a lot of adequate-to-good games don't really do it for him, so his excitement ends up being more infectious than most.
Something I've seen come up often enough to be confused by it in community reactions is the assertion that because something hasn't been explicitly shown in trailers, it won't be in the game. Like, I understand keeping expectations in line, but I also see some of those same people using it to posture the criticism that the game must only have one biome/environment type.
They stated that it will all be based on the PNW and sub biomes with stuff like banished and forerunner bases and war torn areas being cited as examples.