well, they fixed an exploit i saw before, when you gave a city to an ally they got a defensive unit in it, so you could have switched back and forth and got a ton of free units. but again, they fixed that.
one thing i dont like is the simultaneous / turnless mode, i see it as one big problem for civ. imagine having 2 people converging on on city... on the same turn... before you could rally defenses etc... i hink the whole game goes to hell, but i havent seen it yet so i wont jugde it completely
one flaw i see with the current rules is what i do to AI civs i dont like. i offer them a luxury good that i have 0 extra of. i ask for cold hard cash up front. i then move a bunch of workers to the square with the luxury resource, and then i use units to pillage it.
the trade deal is broken and i can rebuild the road and use my own resource.
the AI gets REEEEEEAL mad when you do this, but with human players you could say it was an enemy bombing or something...