Just some bugs/annoyances that I have found. Nothing critical, however I thought I would bring them to light just incase there is a quick fix.
ROLLOVER DATA ERROR occuring on some flags. Not sure how to cause it, but have had it occur a number of times: 
Lighting and other markup effects (like spell/ability circle) are not drawn after game minimisation: 
Note the darkness of all buildings, lack of coloration on the flag, lack of lighting on the Rook and lack of a circle showing me the range of my Rain of Ice. This happens 90% of the time after a game minimisation.
Mouse cursor does not display on game menus after game minmisation: 
Again this happens about 90% of the time after a game minimisation.
I run an 8800gt with nvidia drivers 182.50.
In other news, the latest patch has broken the multiplayer for me, although joining lobbies seems to be more stable and the yellow pings are generally resolved back to green, my game crashes every time the host starts the game (I get a "kicked" message and then the game hangs while waiting for players). Prior to this patch I did not have many/any problems with multiplayer other than problems caused by other players having problems - being unable to join lobbies and connect to everyone.
But, all in all, I thoroughly enjoy the game and appreciate the feedback that Stardock + GPG are giving to the community 
Cheers, Mike