Quick overview: There were two maps in rotation, Warhouse and Wraparound (
both of which have been renamed, but new names aren't final/public yet) - so nothing new there.
The build was dated March 28 - but Frank said it was pretty much a polished-up version of what Devo and Domino played back at the Spring Showcase.
Sounds were all over the map (hmm... bad choice of words) -
some were simply awesome (PLASMA PISTOL OMG), some were missing altogether, others had placeholder versions. (The multiplayer announcer was clearly some guy from the studio. Pretty funny, actually... but I'm glad he's not final.)
I had some trouble getting used to finding Sprint on my left analog stick. (
There are a million button layouts now, so you can pretty much set things up any way you want; I went with my normal (for me) Southpaw/Southpaw/Inverted setup, and that's where Sprint is. Crouch is on the B button, which is bizarre.) Because of this, I felt really slow sometimes.
This was exacerbated by the fact that I'd cranked my sensitivity way down; at the start, I couldn't hold the reticle on my opponents (felt like the equivalent of a 6 or 7 in Reach, so I turned it down from the default 4 to 3), but this made everything else feel... slower. Things were definitely better by the end of the night, and for people less ancient than me, the adaption will almost certainly happen faster.
Loadouts have a couple more slots than Reach loadouts. (In Reach, you get primary weapon, secondary weapon, grenade, AA -
in H4, you get two more slots - I forget what they were called, but they hold things like increased regen and more ammo.) I primarily stuck with the first two loadouts - the first was BR/Plasma Pistol/Plas Grenade, while the second was DMR/pistol/frag.
The DMR is a BEAST at range... but much harder to handle up close.
The BR is a pretty fast killer up close, but at any real distance, you'll get beaten by a good DMR.
The plasma pistol rocks. I don't know if it's just the sound... but DAMN. I was killing people with regular pepper shots (which aren't pepper at all in H4 - they're little mini balls of fire, it seems), and the noob combo is still a reliable annhilator. Overcharged shot seems to track, at least a little bit. (Not as much as Halo 1.

)
Promethean Vision is actually pretty useful in very limited situations. It DOES let you see through walls (at least a limited number of walls; you can see people sort of near you) - but
1) you don't have very much of it (it runs out really quickly) and 2) it doesn't help you figure out where someone is if the geometry is really complicated. I guess this will become less relevant when we know the maps inside and out. It's really useful when someone dips behind a wall and then tries to fake you out... you can tell where they're going.
It also screws up colors, so if you're in the middle of a multi-person firefight, it adds more confusion than it removes. I'd say used judiciously, it's pretty cool - but as Frank said, a good player won't really need it.