First impressions:
1-Yep, looks a lot like 720p.
2-They might need to trim some of the control features. Maybe it's just me being new to Halo 5, but it feels like they're a few mechanics over what works well on that gamepad.
3-The spartans posturing before and after the matches is dumb.
4-Spartan chatter is sort of useful, but annoying. So far my impression is that I'd rather it be removed, but at the very least it needs to be toned down.
5-Killcam music
must be removed, or at least changed to something that doesn't make me want to put a sledgehammer through the XB1.
6-I would have preferred projectiles, and I think the availability of strong hitscan weapons is problematic, though it's nice that the aim assist doesn't seem that strong (I'll see how my opinion evolves as I acclimate to it).
Hopefully I get donged on less badly after shuffling the control schemes a bit, this game really does seem clumsy compared with its predecessors.