Bigger map including half of Africa, India and China.
Diplomacy like in ETW. No more diplomats.
No more non-historical units.
Many nations/tribes. At least three gallic and germanic tribes.
Longer time span. From time before first Punic war to the end of Empire.
More combat animations - soldiers fighting in a much more realistic way - no more "i hit you, you hit me, let's see who is tougher".
Greater variety of faces in a unit. M2TW was in this case better than ETW!
Commands in historic language - no more Romans speaking English.
Maybe some sort of a commanding using your voice? You say "first cohort - advance forward" and your unit advances forward, you say "second cohort - attack cavalry" and your unit does it, and of course... "ALL UNITS - FIRE!"
Ability to create your own general and name him as you please, then observe as his family grows, his children are taking various administrative positions and finally his descendant is becoming an Emperor.
Maybe ability to fight in the battle in Third or First Person Perspective?
Better graphics/physics.
Garrisonable buildings. But all buildings, not like in ETW.
Naval warfare.
Tech tree. But much better than in ETW.