Halo 3: ODST Mythic Overhaul isn't very good.
Sure, it has Elites and Marines on Mombasa Streets, but it's basically the only thing it does well. Oh and the universal ammo box for specific ammo types are great.
The Banished weapons are way out of place and too many "secret" weapons seem to be one off. Pic related shows up at the very end of Tayari Plaza and it never appears again, AFAIK.