Pros:

- You created a nice environment.
- A lot of safe room traps.
- Nice map transitions.
- 2x special infected.
- Scarce ammo which makes it challenging. (Almost a con)
- 5 maps.

Cons:

- Oh my, I don't know if the director was trolling me but... EVERYTHING triggers a horde to the point that it gets VERY exhaustive instead of fun and challenging. There wasn't even time to appreciate the maps or explore.
- Repetitive environments, specially on map 3 & 4.
- One or two bots always dies at the stairs on final map.(Not your fault though).
- Almost impossible with 2 people and 2 bots on expert.
- Finale color filter was annoying (At least for me).

Conclusion:

Oh man when me and my pal finished this campaign on expert we both closed L4D2 and never played for the rest of the day. Very exhaustive.

But I have to hand it to you this is a very well done campaign in terms of aesthetics.