Pros:

-Very good new mechanics.
-Plenty of tight areas providing harder more suspenseful gameplay.
-All maps but the last look very good.
-Can be very challenging. 

Cons:

-The new mechanics were not well used.
-The finale was not very good.
-Way to many hordes.
-To many reused assets from the valve maps in random places. i.e. Gnome Chompski and the float from "The Parish" on the highway on the last map.
-bot survivors get lost and fall off the raft. 
-Supplies can be very hard to come by at some points.

Conclusion:

It could have been much better, every thing is there to have a very good unique Campaign, but it just did not hit the mark. A better use of the new ideas and game Mechanics would have served it very well. The map is still good and playable, but I would not recommend it if your looking forward to fighting a Giant tank or looking for awesome new Game Mechanics that you will be forced to use.