Halo reach needs more open maps imo. Something to push the distance of fights from melee range to mid/long range.
With the addition of movement based abilities the speed at which players close range, and the general distance between shootouts has shrunk in comparison to previous halo games. Those same abilities also speed up the rate of player encounters.
I think it's just a bit too common to be turning a corner and be forced into a beat-down match, or to face sprinting hammers/shotgun/beatdowns. I also find it pretty common to just finish a player kill and have that same player you just killed jet-pack or sprint to a position to take you out.
It's also frustrating to get stuck onto a piece of scenery while grenades are going off, this has happened to me a couple times on powerhouse, just with the edges of catwalks.
I'd really like to see the geometry in maps scaled back, and open up the playing field a little more, keeps sections closer quarters, but make routes from these sections a bit more visible.