Pros:

-Very detailed, lots of things for the eyes to see, and neat little details to distract oneself with
-Great level design, levels are large and somewhat open-ended, but you're never lost for more than a couple moments if at all.  The signs are easy to follow.
-Custom music sounds wonderful! It's not cheesy nor melodramatic!
-Custom graffiti is fun to read, Chicago Ted's admirer's are funny.  Also neat to see the fourth wall broken in graffiti too.
-Great visuals, each level is designed with artistic flair, the mansion is a real treat to explore!  
-Though it has its humor, the campaign is believable, the environments make sense, and military camps and such look logically placed.
-L4D1 characters!

Cons:

-It's the only campaign of its quality

Conclusion:

The best campaign I've played hands down, tops even Valve's campaigns.  It's immersive, has subtle humor, is well-designed, looks good, plays great, and is one to share with friends.  

I sincerely hope to see more from you! This is top-notch stuff and really stands out from the crowd.