Pros:

Good length
Custom voice acting
Runs smoothly, no  major bugs
Complex finale

Cons:

The main con for me is the same looking locations
Lots of empty rooms
Too many directional signs (I'm ok with them, but not if I see them on every wall)
Sometimes you can notice copy/paste stuff here and there
Custom music doesn't really fit the game

Conclusion:

It's nice at the beginning, but then quickly gets repetitive and boring because of the same looking environments all the way. Just finished it, but I barely can remember anything other than tonnels, cars, hangars and industrial shelvings. A lot of hangars. A LOT of industrial shelvings. The finale was fine. I like how you combined it, although it was too easy to survive.

Obviously you did hard work, but I think the design could be more interesting for an ambitious project like this. Seven years have passed since L4D has been launched and I think we've seen a lot of custom campaigns with cars, hangars and tonnels (along with very creative and interesting ones). And I hope I wouldn't sound too demanding if I say that I expect something more creative from l4d map makers today. All in all good job, but it's too ordinary for me.