Pros:

+  Excellent level design & attention to detail

+  Excellent use of custom music, atmosphere  & "flavor text"

+  Great use of crescendo moments

+  Good pacing & item distribution

Cons:

-  Final in-game rescue cut scene could have been better

-  I can't shoot through razor wire...?

Conclusion:

My brother and I had a blast playing through this campaign.  Very high quality with custom music, loading screen poster, graffiti, weather effects, new recorded voice acting, great level design and so much more.  This could easily pass as official content.

My gripes are few and really just nit-picks:  I was frustrated that I couldn't shoot at infected through some razor wire strung across the top of some cubicles, and I thought that the camera and lighting could have been better for the  final rescue in-game cut scene.

I heard some people encountered a few bugs; the only one I experienced after playing through once was a graphic error on returning to the lobby after completing the campaign.