It's the same as normal Munchkin, except the "Monsters" are normal people, and the Munchkins are Zombies.  Being zombies opens up some funny bonuses and curses you couldn't otherwise do.  For instance, losing an arm so only a single 1 handed bonus can be used; or using a detached leg as a hand weapon.

The only new mechanic I could see was the concept of "Powers".  Rather than Race and Class like in standard Munchkin, you have Mojo and Powers.  Powers have a "rank" attached to them, such that you can only apply them as long as the total rank is less than or equal to your level.  Since there are no rank 1 powers, you can't start with any.

The Good: Same Munchkin humour.  Can be combined with standard cards.
The Bad: Doesn't add much to non-Zombies version
The Ugly: Cards feel cheaper

Recommended if you love Zombies, don't already have any Munchkin sets, or just collect anything Munchkin.  Otherwise, you're not really missing anything.