They definitely fucked with things in this one. The pack-a-punch being separated from the main map is an interesting choice. Also, saving wonder weapon parts until level 16 or later is a move. (You could get the die by 10 or 11 on Die Maschine. Even earlier with the coffin dance.) It's still early, but the zombies seem to be stronger and faster.
still, i'm happy they're supporting it. this game is fun as hell. I don't even play multiplayer. (they botched that anyway.)