I really wish the meter for blowing circles stayed through out the game, I found the start of level 4 insanely hard because blowing three in a row is hard.
I encountered a bug. If you start the tutorial and at the point where you have to buy ten zombies go to the menu, then select new game same difficulty. Then the game starts you can't do anything, without the message about buying ten zombies, which is impossible to do.
Also you should be able to quickly see which player was who.
One of my players seemed to have the stats of a tank, but I had no idea of where he was placed on the field.