I'm not certain it will be as amazing for MP as people suggest. I used to play vanilla Civ5 MP - it's not that bad, because the Civs/Leaders are pretty baseline, there is nothing too crazy, not too many factors to consider besides your actual playstyle.
I'm worried that all these dozens and dozens of bonuses for each Civ will make the game unbalanced, combined with the combo-system, the "any leader" system - it sounds like there will be eventually overpowered combinations...
This sounds like a negative thing for multiplayer. People will eventually discover all kinds of awful loopholes that will make entertaining YouTube videos (How To: Build 7 units in one turn)
My basis for saying this is that pre-day-1 Spiff already found crazy exploits for Egypt.
Now, combating terrible balance is a fat reset button which may or may not solve this problem depending on implementation. It's to be seen, but I'm hesitant to basically say that the MP is going to be amazing straight off the bat.
I'm more easily convinced that it will actually be a horsehockyshow - a very entertaining one though