Pros:

Very cool, realistic landmarks.
Big, immersive maps.
Good placement of weapons and ammo.
Lots of special infected (I killed 120!)
Great penalty for trying to run past the finale! There's a  very logical reason to take the train!

Cons:

None for me. Big maps may be a con for some.
Normal may be too hard in single player for some.

Conclusion:

Excellent campaign! I highly recommend it. I also recommend, if you have Nvidia, to use beta driver 331.40 and enable 'Quality' Ambient Occlusion in the L4D2 profile, as it will add more realism and enhance this already beautiful campaign :D