Pros:

Original script events, would be scary if playing alone.
Artistic touch on the water details. 

Cons:

Tier 1 weapons too far from start
Excessive horde spawns
Safe house for level 1 out in the open
Zero direction on "maze" event

Conclusion:

Even playing with a friend, I found this campaign to be tedious.

Starting off without tier 1 weapons is not a big deal, provided you don't have to fight constant special spawns before you reach them. We killed 7 specials before getting subbies. Not a big deal unless 4 of them are chargers in a narrow/zero movement corridor.

In the first map there were a ton of .50 cal HMGs to use, but the horde was always rushing from the other direction (atmosphere maybe?)

Excessive rushes from step 1 outside the safe house, every 45 seconds. Offset slightly by a lot of weapon spawns after the subway station. Jesus Christ do you need them. 

First safe room made zero sense at all. If standing out side in the middle of a zombie apocalypse is your idea of safe, maybe you worked for CEDA.

Sense you mentioned you learned HAMMER for the purpose of making an article for it, I won't bash the idea of a castle in North America,  (if it's else where, I saw no indication of the survivors being in another country). But having a script to startle your audience is usually done better when you don't have waves of infected punching their faces in.
I personally triggered the first "witch attack" event, and shoved out of reflex and it was gone, leaving me to focus on the infected and not even give it a second thought. Same thing with the witch on the ceiling, I would have shot at her if not for fighting infected.

"Maze" event utterly irritating. Infected dropped on us nonstop. I figure you use triggers to cause them to spawn when we reached certain areas, but this proved too much when trying to find our way around. We had rushes for 10+ minutes. When we reached the end of the maze (or as far as we got in it), we became stuck trying to fend off the horde. 

Too much effort on our side for no real pay off.