I've played the competitive version a few times and it plays like Zombies only a little better.
The four farms force players to cover the board. Collecting the item tokens to build the bomb does the same thing. It's not useful to try to kill fewer martians so you can place the helipdad. There is no helipad to be had and the farms are placed by the person who draws them.
The change to movement = d6+ health is a good one and also speeds up the game.
I think some of the green cards are too powerful, but most of them affect all players (including you) so it's not as bad as it could be.
Overall I think it's an improvement in play over Zombies!!! and I like Zombies!!! I don't think I like it quite as well as MidEvil, but I definitely plan to play it more.
I haven't played the coop version yet, so I can't really speak to it. Strangely most people I've played with have wanted to go the same way as before - everyone for themselves.