Pros:

Interesting lighting 
Very moody and ambient
sometimes too dark to see what's happening (pro)

Cons:

sometimes too dark to see what's happening (con)
Endless hordes

Conclusion:

Thanks for the campaign but I found it frustrating due to the endless hordes and haven't managed to finish map 1.  From reading other comments this sounds a great map but the difficulty level is high - I'm playing it on normal.  I will have a try at playing on easy to see if I get any further into the campaign and if so will amend my rating.