I'm probably not the first person to notice this but I also haven't seen anyone else mention it. Yeah they changed it, you'd think they'd just use the architecture on the chief from Reach, or at least similar to it. Having said that, I'd like to invite everyone to watch the anniversary trailer (has to be in HD) and forward to the segment where it says "co-op over xbox live", roughly 1:15 in depending on where you watch it. look closely, the second chief playing along with the first person is clearly visible as the same model from reach. Personally, I'd prefer it that way, I think the Reach aesthetics are the best yet, but thats just me.