A very nice scenario. I'm already addicted to it.
Some "experiences" I made:
I've played with all races and it's not too hard to win with any of them. Zombies are really easy. The survivors are easy too if you rush with the king units and "free" the graveyard and the hospital and take the store qucikly (chainsaw maniacs) - there is no need for the helicopter. Authorities and the company are a little more difficult, but also easy, if you rush zombie-cities (except those 7 with king inside) and destroy them with the king units - both of them, but especially the authorities - can't defend them. (at least I wasn't able to do this)
One thing is common: The AI is extremely stupid. As Zombie it's ok - it stacks the units to a horde and take one city after another. As Survivors it doesn't use the King units properly and as the company it uses them too stupid (the director has no properties - neither offensive nor defensive, so he just runs around). I've noticed that the SWAT-Teams are made as "offensive"-units, which results that authorities don't defend their cities and lose them all, except the city hall and military base. With off 5 they are often not able even to kill one Zombie in suburbs or downtown.
Also it is often really frustrating with "luck". I don't know how often I lost Hank with def 10 (Elite) beyond barricades, fortified in a city, just to 2 or 3 Zombies - SWAT-Teams are near to useless

. Also it's really hard to get some ressources - as Survivors I lose my 4 food parcels (with graveyard) within 10-20 rounds. Ammo is problematic too, but the survivors have at least the chainsaw maniacs. As the Authorities it's really bad, because I got in the most games exactly 2 units: SWAT-Teams and cruisers (and cruise missiles for the armoury and the research lab).
Oh, btw. If there is some place free, all destroyed civilisation "restart" the scenario with 1 city, is this a bug?
Anyway - a really great scenario and I ennoyed it really!
Oh, befor I forget - I don't know why, but every time when I set the research-slider to 10%, next turn it's "resetted" to 60% again. It's really annoying, does anybody knows how to avoid this?