Carl2291 said:
Reach already has the ultimately awesome Needler Rifle. Reach wins. |
And the DMR (One shot Battle Rifle):

Halo CE pistol Spiritual successor:
Plasma Launcher (Covenant type of missile mod)

Plasma Repeater (New Plasma Rifle replacement for multiplayer):

Focus Rifle (Sentinel Beam and Beam Rifle had sex):

Needle Rifle (Needler and Carbine had sex):

Grenade Launcher (+ Emp Launcher):

They're just the new weapons announced so far. Oh and the Gravity Hammer and Energy Sword are in Halo Reach. (You can see them being used in the Alpha Build multiplayer Beta trailer).
Elites are also more badass and no longer weighed down by the multiplayer balance. Leashes are finally off!
They're stronger, much faster and more agile and also feature better shield systems and health regeneration. They'll only be available in certain gametypes. No more asking for Gas 

Some other new awesome screenshots:
Assassination:

Armor Lock Down ability (particle effects are lacking in the current build.)

Jetpack:

Sprinting:

Pretty funny kill with the Gravity Hammer on an custom infection game on Halo 3:








